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Full text of "Practical Wireless 1967 February"

. FEBRUA 
1 1967 



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/3DCOLC\ 

^m^mimm.'- ■ ■ ■- "■-•ammmmmmm 

'«.,« '••«. «...! 

SOLDERING INSTRUMENTS 
AND EQUIPMENT 




DESIGNED FOR 
THE AMATEUR'S 
RADIO STATION 



ILLUSTRATED 

List No. 70 |* BIT 

IN 
PROTECTIVE 
SHIELD 
List No. 68 



for catalogue apply direct to: — 
Sales and Service Dept. 
ADCOLA PRODUCTS LTD., 
ADCOLA HOUSE, 
GAUDEN ROAD, 
LONDON, S.W.4 



Telephones 
MACaulay 0291/3 



Telegrams 

SOLJOINT LONDON SW4 



JACKSON 

the big name in PRECISION components 

Precision built radio components are an 
important contribution to the radio and 
communications industry. 




SL 16 
DRIVE 



A general purpose slide rule Drive for F.M./V.H.F. 
Units, short-wave converters, etc. Printed in two 
colours on aluminium, with a 0-100 scale and 
provision is made for individual calibrations. Com- 
plete with bronze escutcheon and glass. 



It's reliable if it's made by Jackson! 

MADE IN ENGLAND 

JACKSON BROS. (LONDON) LTD. 

Dept. P.W., Kingsway-Waddon, Croydon, CR9 4DG. 

Telephone: Croydon 2754-5 (01 -688) 

Telegrams: Walfilco, Croydon 



NOMBREX 



INSTRUMENTATION 




WIDE RANGE 
TRANSISTORISED 
SIGNAL GENERATOR 
MODEL 27 

*Range 1 50Kc/s-350Mc/s 
•£ Direct Calibration 
■jfc Mod. or Unmod. output 
-£ Accuracy better than 2% 
£10.16.9. 



ALSO AVAILABLE 

C. R. Bridge 62 . . £9.6.9 

Inductance Bridge 66 .. £18.6.9 
Power Supply Unit 61 . . £6.14.6 

WIDE RANGE TRANSISTORISED 
AUDIO GENERATOR 63 

ic Range lOc/s-lOOKc/s 
■^ Sine or Square Wave 
■^ Accuracy & Low Dist. 
~k Calibrated Output 
£17.1.9 



All prices include battery, post and packing 

S.A.E. for Trade & Export Prompt 

Leaflet Enquiries Invited Delivery 




NOMBREX LTD 

Estuary House, Camperdown Ter., Exmouth, Devon 



INSTRUMENTS 
DIVISION 



ENORMOUS PURCHASE GUARAN- 
TEED. APPROX. HALF PRICE. 
WORLD FAMOUS MAKE 

• TAPE • 



We offer you hilly tensiliscd polyester/ 
mylar and P.V.C. tapes of identical 
quality hi-B, wide range recording 
characteristics as top grade tapes. 
Quality control manufacture. They 
are truly worth a few more copper* 
than acetate, sub-standard, jointed or 
cheap import*. TRY ONE AND 
PROVE IT YOURSELF. 



Standard Play 
3in. 150ft. 2/3 
4in. 300ft. 4/6 
Sin. 600ft. 7/6 
5 4 "in. 900ft. 10/6 
7in. 1.200it. 12/6 

Double Play 
3in. 300ft. 4/- 
4in. 600ft. 8/- 
oin. 1, -200ft. 15/- 
iijin. l.SOOft. 19/6 
Tin. 2,400ft. 27/- 

PoKtagc 1 /- re el . 
Post Free less 5^ 



Long Play 
3in. 225ft. 8/9 
4in. 450ft. 5/6 
5in. 900ft. 10/6 
5Jin. 1,200ft. 13/- 
7in. l.SOOft. 18/6 

Triple Play 
4in. 900ft. 13/- 
oin. l.SOOft. 25/- 
ojin. 2,400ft. 34/- 
7in. 3,60Oft. 44/- 

Qnadruple Play 
31n. 600ft. 8/6 

i three reels. 



Quantity and Trade enquiries invited. 
NOTE. Large tape stocks at all branches 



BARGAIN PARCELS 



Imlu. 
speak' 



3 lbs. 
7 lbs. 
14 lbs 



ing variable condensers, i.f. coils, loud- 
a-ptags /si.ckfts.kimlis, pots, condensers, 
rs, nuts, bolts, cabinet rit tings, vwitcbes; 
iinncr choke, rectifier, transistors at a 
traction of list value. Dot to heavy 
id we are now packing them in several 
TRY ONE. 

lpost8/-> 9/- 

(post5/-) 17/6 

post 6/-) 88/- 



Transistorised 

FM Tuner 



CALLERS WELl 



*..»*,:*.. 




HIGH QUALI1 
LOW NOISE: 
BATTERY OR 
OPERATION 



m 



m 



15 Watt 

TUNER AMPLIFIER 

KIT 

14 TRANSISTOR 

consisting ol FMT41 tuner 
and the excellent Sinclair 
Zi2 (built) together with 
complete integrated control. 
Kit consisting complete vol. 
on oil. treble and bass, 
component sets with com- 
plete connecting instructions 
and cirouits, battery version 

£13.19.0 

or complete with AC mains 
power pack £17.18.6. 
STEREO VERSION with 2 
Z12 amplifiers £18.10.0. 
A.C. STEREO i'22.10.0. 



This beautilully comiact 
transistor machine laize 
i 4 x 2! in.) will give guiet- 
more interference free re- 
on. Months of use from a 
ird 9 volt battery or its 
ower requirements can be 
rom any amplifier. Low 
equency changer with 
,ang tuning feeding no less 
I.F. stages coupled to a 
•iminator terminating in 
ag ample output lor all 



quality ampnne 



avoid disappointment 

ORDER NOW £8-1 



LATEST 

GARRARD 

All Factor// Fresh. Ml leith cartridge. 

EV26 Ctramk Stereo cartridge fined to 
any deck for 15;- tttrVh 

SRP12 £4.7.6 

SP25 £9.19.0 

AUTOSLIM £5.10.0 

Model 1.000 £6.6.0 

Model 2.000 £6.10.0 

Model 3,000 £8.10.0 

AT60 £9.19.0 

A70 £18.10.0 

LAB80 £24.19.0 

401 £29.19.0 

BS.R. BARGAINS 

TU14 59/- 

GU7 85/- 

UA14 89/- 

UA16 99/- 

UA25 SUPERSLIM £5.10.0 

CARTRIDGES 

G.C.2. Garrard Mono 16/- 

EV26 Garrard Stereo Ceramic 24/- 

EUPHONIC SUPER Ceramic 
Stereo Diamond lOOmV 
Output 29/- 



TRANS/CEIVERS 

The very latest Silver/Black finish. They 
give an excellent performance with reliability, 
long telescopic aerial, crystal controlled. 
Note a licence is required to transmit. They 
compare with much dearer &c -ion 
models. 2/6 p. « p. *•"■' «».U 

These cannot be operated in U.K. 



STEREO FM HERE! 



iiiiiai 




From Denmark"; Lnr« 



THE NEILS0N 'ARENA' T1900H 

All waic AF/1'M stereo receiver amplifier. 5 wave hands. 2 
.sinus pressnre-chamber speakers, 8 watts, four channel. 
Fully transistorised, natural oiled teak cabinet, internal/ex- 
ternal speaker, A.F.C., FM & AM tuning controls, internal or 
external aerials, tape recorder, gram inputs. 200/250 v. A.C. 
operation tuning indicator, bass, treble volume cc p nc 
controls. Size 29Jin. x SJin. x 84.in. oa u,la - 

Or complete with Stereo Multiplier, as stocked en fine 
m all branches. °* ul, »- 




As above, less CO fin*; 

speakers aa «'•*»■ 

Arena Hi-Fi speakers stocked at all branches. 
CALLERS. Wide range of Hi-Fi equipment aeailabli at all 
'.v,„ ,v,. WE OFFER PACKAGE DEAL DISCOUNTS. 



ARENA T1900F 



purchase we can offer these bla^k/satin chrome receivers 
normally approx. 15 j^ns, covering hill medium wave and 
l''.M- bands. Built-in aerials, medium size, Ql P nc 
with baft. 3 2 "» S - 

ALL BRANCHES have a icide range of transistor sets from 
55/- to £70. 



TRANSISTOR 

POWER PACKS 

9 or 12 volt \\ amp 

Transistor and zener voltage and ripple 
controlled giving variable controlled sta- 
bilised voltage minimising amplitude distor- 
tion due to varying power pack output 
voltages due to varying current drawn by 
class B transistor amplifiers. 
200/250 A.C. input 



55/- 



GUARANTEED 3 MONTHS 
BY RETURN OF POST 



Value in VALVES 

Satisfaction or Money Back Guarantee on goods If returned unused within 14 days. 
ALL VALVES AEE NEW UNLESS OTHERWISE INFORMED. FREE 
TRANSIT INSURANCE. POSTAGE 1 valve 9d.. 2-11 6d. per valve. Free over 12. 



1L4 

1R5 

1S4 

1S5 

1T4 

2D21 

3A5 

3Q4 

5TJ4G 

5Y3GT 

5Z4G 

5Z4GT 

6 30L2 

6A8G 

6AK5 

8AQ5 

6AT6 

6BA6 

8BE8 

6BH6 

6BJ6 

CBR7 

6BW8 

6BW7 

8C4 

6C5 

6C8 

8C9 

6CD6G 

6D6 

8F1 

6F6G 

8F13 

8F14 

6F15 

6F23 

8I5G 

8J5GT 

6.T8 

8J7G 

6J7GT 

6K7G 

6K7GT 

6K8G 



2/3 1 6K8GT 
4/9 8L1 
4/9 6L6G 
4/6'6L18 
3/-.6LD20 
5/8 6F25 
6/- 6P28 
5/3 6Q7G 
8/- 6Q7GT 



9/8|20P4 17/9ECCS8 
9/6 25L6GT 7/-ECI80 
8/8 25Z4G 7/- ECF8S 



7/9I30F5 
S/6 30FL1 
12/- 30L15 
9/6 30P4 
7/- 30P12 
8/9 30PL1 



6SL7GT 6/9 35A5 



6SN7GT 6/9i35L6GT 8/6 



8U4GT 

6V6G 

6V8GT 

6X4 

8X5G 

6X5GT 



I36W4 
4/9 35Z4GT 5/9 
6/9 30L6GT 8/6 



9/- ECH21 10/- 
ECH35 11/- 
ECH42 10/6 
ECHS1 6/9 
ECH83 7/9 
ECLS0 5/9 
ECL82 7/6 
ECL83 10/6 
ECL88 9/6 
EI 36 
EI39 
EF40 



11/8 

11/6 

M- 

u/- 

9/6 



7/6 
185BTA19/6 EF41 



7C5 

7C8 

7H7 

7S7 

7Y4 

10C1 

10C2 

10F1 

10LD11 14/8 

10P13 9/6 

10P14 

12AT7 

12ATJ7 

12AX7 

12J7GT 



11/6 
7/8, 

9/6 A231 8/6 
7/8 CBL31 19/6 

DAF96 7/3 

DF96 

DK82 

DLS6 

DL92 

DL94 

DLB6 



14/6 

7/- 

11/- 

12/6 

7/6 



7/3 
EABC80 6/9 



EAF42 
EB41 
EB92 
EBC33 



9/6 

4/9 

5/6 

6/-, 

9/- 1 EBC41 
12K7GT 5/-iEBC91 
12K8GT 9/6IEBF80 
12Q7GT 6/6EBF89 



14S' 
19AQ5 
20D1 
9/6;20F2 
2/8 20L1 
5/9 20P1 
5/9 1 20P3 



14/6 
5/6 
8/9 
9/6 

16/- 
9/6 
9/6 



7/9 
7/- 

EBL21 11/- 

FCC40 

FCC81 
FCCS2 
ECC83 
FCC84 
ECC85 



EF50 

EF80 

EF85 

EF86 

EF89 

EF91 

73 ! EF18S 

8/6 EF184 

73 EL32 

EL33 

EL 34 

EL35 

EL38 

EL41 

EL42 

EL84 

EMS0 

EM81 

EM84 

EY51 

EY86 

EY88 

9/6IEZ40 

4/9'EZ41 

5/6 1 EZ80 

6/- E781 

7/- FC4 

5/9IGZ32 



GZ34 


10/fi 


Kiel 


12/- 


KT63 


h/» 


KT66 


19/H 


KTS8 


27/6 


K1W6: 


h/H 


ktwb; 


W- 


KTZ63 


7/- 


MTJ14 


7/- 


N37 


H/H 


N78 


13/- 


N108 


13/- 


PC86 


H/H 


PC97 


7/6 


PCC84 


H/« 


1CC85 


7/8 


PCC88 


ll/H 


PCC89 


11/- 


PCC18! 


H/H 


FCF80 


«/» 


FCF82 


K/H 


PCF86 


8/3 


FCL82 


7(9 


FCL83 


H/B 


FCL84 


9/- 


PCL85 


»/« 


PCL86 


H/H 


PL33 


8/H 


PL36 


11/- 


PL38 


IK/H 


PL81 


7/9 


PL82 


5/9 


PL83 


6/- 


PL84 


•II- 


PY31 


■;/« 


PY32 


9/8 


PY33 


7/8 


PY80 


5/9 


PY81 


h/H 


PY32 


ft/H 


PY83 


w» 


PY88 


8/H 


PY800 


;/- 


PZ30 


9/6 



SP61 

TDD4 

TJ14/18 

U25 

U26 

U35 

C37 

TJ107 

D191 

C281 

D282 

U329 

US01 



2/9 
ft- 

7/6 
9/6 
9/6 
12/6 
11/- 
12/6 
12/6 
9/6 
15/- 
8/6 
19/- 



TJABC80 6/6 
DAF42 7/9 
UB41 6/6 
UBC41 8/9 
TJBC81 6/9 
UBF80 7/6 
TJBF89 7/6 
TJBL21 10/9 
UC92 6/9 
UCC85 7/3 
TJCF80 8/6 
LCE21 10/9 
DCH42 8/8 
DCH81 7/- 
D0L82 8/- 
UCL83 10/6 
DF41 9/- 



UF42 

UF85 

UF89 

DL41 

TJL44 

TJL46 

TJL84 

TJM80 

UY21 

UY41 

TJY85 

VR105 

VR150 



100 HI-STABS 



9/6 



1% to 5% 100Q too ma. 
CO-AX. low loss. 6d. yd. 25 yds. 11/6; 
50 yds. 22/-: 100 yds. 42/6. Plugs 1/3. 

100 RESISTORS 6/6 

SIZES J-3 watt. 

MICROPHONE CABLE. Highest 

quality, black, grey, white, 9d. P'T 
yard. 

100 CONDENSERS 9/6 

Miniature Ceramic, Silver. Mica, etc. 
3pFtoo|iF. LIST VALUE OVRR £4. 

25 ELECTROLYTICS 

Assorted 2 to 500 mfd « to 400 _, c 
volt. LIST VALUE OVER £5. 9; O 

50 TAG STRIPS 7/6 

Mixed sfees 2 to 15 way. 

ELPIC0 MONO PREAMPS 

DPA15. Latest black'satlu chrome 
finish multiple input channela selec- 
tor, bass and treble controls. Matches 
all pick-ups and mikes. Provision 
tape recording, formally 
10 gns. our price. 



5 Gns. 



TRANSISTORS 

GUARANTEED TOP QUALITY 
Mullard Matched Output Kits 
OC81D and 2-OC81 
R.F. Kits OC44, OC45 (2) 3 



9/6 
9/6 

GERMANIUM DIODES 

General Purpose miniature j»j 

detector A.V.C. etc 6/6 doz. OO. 

Gold Bonded highest quality. ^ / 

Individually tested 9/6 doz. ■/ 

SILICON RECTIFIERS 

Guaranteed performance. Top makes. 
Tested 260.V. working. 

120 ma. „ /Q 500 ma. -, R 

(3 for 8/6) */!' (3 for 19/6) «/© 



Storlixt* of Leak, Quad, Chapman, Goodman, Aniulnna, Triple/one 
Post: 1 lb. 1/5, li lb. 2/6. 2 lb. 2/9, 4 lb. 3/3, 6 lb. 4/-. 14 lb. 5/6. 



ECHNICAL 
JRADING 



ttrnx, Ftiroyr'iph. tt'harfedolc. etc. 
All Mail Orders to Brighton please 



10 Tottenham Court Road. W.l. 
Tel. MUSeum 2639 



LONDON 



BRIGHTON & k 6 c 8o?2T tPlac6 



350-352 Fratton Road 
Tel. 22034 



PORTSMOUTH 

Southampton as&r 

WORTHING %.&»•"" 



713 



HIGH GAIN 4 TRANSISTOR 
PRINTED CIRCUIT 
AMPLIFIER KIT 
Type TA1 

• Peak out-, 
put in exeess 
of Ik watts. 

• All stan- 
dard British 
components. 

• Built o 
printed circuit 
panel, size fi x 3i 

• Generous size Driver and Output Transformers. 

• Output transformer tapped for 3 ohm and 15 ohm 
speakers. • Transistors (GET 114 or SI Mullard OC81D 
and matched pair of OCS1 o/p). # 9 volt operation. 

• Everything supplied, wire, battery clips, solder, etc. 

• Comprehensive easy to follow instructions and 
circuit diagram 1/6. (Free with Kit). All parts sold 
separately. 

SPECIAL PEICE 45/-. P. & P. 3/-. 

Also ready built and tested, 52/6. P. & P. 3/-. 

A pair of TAls are ideal for stereo. 




STEREO AMPLIFIER 

Incorporating 2 ECL86s and 1 EZ80, heavy duty, 
double wound mains transformer. Output 4 watts 
per channel. Full tone and volume controls. Absolutely 

complete. 

ONLY 

£4.19.6 

P. & P. 6/8 

Super De- 
luxe version 
withECL8S 
valves sepa- 
te bass, treble and balance 

controls. Full feed back. 8 gns. 

P. & P. 6/6. 




6 TRANSISTOR AND DIODE 
SUPERHET 

A first-class 2 waveband transistor superhet. # Printed 
circuit panel (size 81 x 22in.). • 3 pre-aligned IF 
transformers. • High-gain Ferrite Rod Aerial. • All 
First-grade transistors. • Car aerial winding. • Push- 
pull output • All parts supplied with simple instructions. 
All parts sold separately. Set of parts if purchased at one 
time ONLY £4.5.0. P. & P. 2/6 (Circuit diagram 2/-. 
Free with set of parts.) 

35 OHM SPEAKERS 

Suitable for use with above. 2in. Goodmans. Ideal re- 
placement for most pocket portables, 8/6; 3Jin. 12/6; 
7 x 4in., 21/-; P. 4 P. 2/- per speaker. 

Portable CABINET 

Size approx. 9i x 6{ x 3Jin. Suitable lor above using 
3{in. speaker, 25/-. P. & P. 2/6. 

COIL AND TRANSFORMER SET 
FOR TRANSISTOR SUPERHET 

3 IF transformers one oscillator coil one driver trans- 
former and wound Ferrite aerial (med. long and car 
aerial coupling), 32/6 complete post 2/-. 6 transistor 
printed circuit board to match 8/6. Post 1/-. Circuit 
diagram 1/6 extra, 



MINIATURE PRECISION AIR-SPACED TWO GANG 
TUNING CONDENSER. 176 4-176 p.F. size IJ'w x §"d x 
V.'h with vanes open. Built in trimmers 5/-. P. & P. 1/- 

BRAND NEW TRANSISTOR BARGAINS 
GET 15 (Matched Pair) 15/-; V15/10p, 10/-; 0071 
6/- ; OC76 6/- ; AF117 7/6. 

Set of Mullard 6 transistors OC44, 2 — OC45 OC8ID 
matched pair OC81 25/-, ORP12 Cadmium Sulphide 
Cell 10/6. 

EDISWAN MAZDA 
PXA101 6/6; XA103 6/6. 
R.F.I. Pack: 1— PXA102 Mixer; 2 — PXA101 l.F. Amp. 

(Eqniv. OC44 and OC45) 10/6 

E.F. 2 Pack: 2— PXA101 l.F. 1— PXA102 Osc.l — 

PXA102 Mixer 12/6 

L.F.6 Pack: Consisting of PXB113 Driver Matched pair. 
PX171 mounted complete with heat sinks (Equiv. 

OC81D and OC81) 12/6 

ALL TRANSISTORS POST FREE. 

~~~ TAPE DECKS 

B.S.R. MONARDECK (Single speed) 3Jin. per sec, 
simple control, uses 5; in. spools, £6.15.0 plus' 7/6 carr. and 
ins. (Tapes extra). 

LATEST COLLARO MAGNAVOX 363 TAPE DECK 
DE LUXE. Three speeds, 2 track, takes up to 7in. spools. 
10 gna. Plus 7/6 Carr. & ins. on each (Tapes extra). 

PORTABLE TAPE RECORDER CASE 

Beautifully made and expensively finished in dark 
grey heavy grade rexine. Satin Chrome metal grille 
front and chrome fittings. Speaker aperture 9" x 4". 
Overall size 151" w. x 16" d. x 7i" h. Will take any 
standard tape deck or single record plaver. Limited 
number only. Worth at least £5. OUR PRICE 49/6. 
P. & P. 5/-. Brand new and unused. 

ACOS CRYSTAL MIKES. High imp. For desk or hand 
use. High sensitivity. 18/6. P. 4 P. 1/6. 
TSL CRYSTAL STICK MIKE. Listed at 45/-. Our price 
18/8. P. & P. 1/6. 



QUALITY RECORD PLAYER AMPLIFIER 

A top-quality record player amplifier. This amplifier 
(was used in a 29 gn. record player) employs heavy 
duty double wound mains transformer, ECC83, EL84, 
EZ80 valves. Separate Bass, Treble and Volume controls 
Complete with output transformer matched for 3 ohm 
speaker. Size Tin. w. x 2Jin. d. x 5iin. h. Ready built 
and tested. PRICE 69/6. P. & P. 4/9. 
ALSO AVAILABLE mounted on board with out- 
put transformer and din. speaker ready to fit into cabinet 
below. PRICE 89/6. P. & P. 5/9. 

QUALITY PORTABLE R/P CABINET 

Uncut motor board. Will take above amplifier and 
B.S.R. or GARRARD Autochanger or Single Record 
Player Unit. Size 18 x 14 x 8 Jin. 
Price £3.9.6. Carr. 7/6. 

4-SPEED PLAYER UNIT BARGAINS 

All brand new in maker's original packing. 

SINGLE PLAYERS 

B.S.R. TU/12 £3.9.6 Carr. 3'6. 

GARRARD SP25 De Luxe . .£12.10.6 Carr. 5/6. 

B.S.R. GU7 with unit mounted pickup arm. 

£4.18.8 Carr. 5/6. 

AUTO CHANGERS 

Latest B.S.R. UA25 Super slim £6. 2.6 

GARRARD 1000 with special Hi-Fi cartridge. . £6.19.6 

GARRARD AT6 £9.10.0. Carr. 6/6 on each. 

All the above units are complete with t/o mono head 
and sapphire styU or can be supplied with compatible 
stereo head for 12/6 extra. 

BRAND NEW CARTRIDGE BARGAINS I 

ACOS GP67-1. Mono complete. List price 21/-. Our 
price 13/6. P. & P. 1/-. 

BRAND NEW 3 OHM LOUDSPEAKERS 

5in„ 12/6; 6Jin., 15/-; 8in., 21/-; 10in„ 25/-; 7in. x 4in., 
15/-; lOin. x 6in„ 26/-. 

E.M.I. 8* x 5" with high flirx ceramic magnet, 23/6. 
E.M.I. 13J x 8iu. with high flux ceramic magnet, 48/- 
(15 ohm, 45/-). P. & P. 5" 2/-, 6£" & 8" 2/6, 10" & 12" 
3/6 per speaker. 



SPECIAL OFFER I 

Limited number of 12in. 10 watt "R.A." Speakers: 
3 ohm 25/-; 15 ohm, 27/6. P. & P. 3/6. 



E.M.I. PLASTIC CONED TWEETERS. 2f 3 ohm. 
Limited number 12/6 each. P. & P. 1/6. 
BRAND NEW HEAVY DUTY 12in. SPEAKERS 
Response 46 e/s-13 Ku/s. liin. voice coil. Available 
in 3 or 15 ohms. Guaranteed full 1 5 watts British rating. 
Heavy cast aluminium frame. These are current pro- 
duction by world famous maker and as they are offered 
well below list price we are not permitted to disclose the 
name. LIMITED NUMBER ONLY. UNREPEATABLE 
at 89/6 P. 4 P. 5/-. Also 25 watt Guitar Model available 
at £5.5.0. And 35 watt Guitar Model £8.8.0. 

VYNAIR AND REXINE SPEAKER AND CABINET 

FABRICS. 

Approx. 54in. wide. Usually 35/- yard. OUR PRICE 

13/8 per yard length. P. 4 P. 2/6 (min. one yd.) S.A.E. 

for samples. 



SPECIAL OFFER! 

GENUINE HIGH QUALITY TYGAN FABRIC. 
48in. wide. Our price 10/- per foot run. 1*. & P. 1/6, 
30/- per yard run. P. « P. 2/6. 



SEMI SHROUDED DEOP THRO' MAINS TRANS- 
FORMER. Tapped pri 200/250 v. Sec. 300-0-300 v. at 
110mA. and 6.3 v. at 3 amp. (E/S screen). Stack size 
3J x 3J xljm. 30/-. P. & P. 3/6. 

MAINS TRANSFORMER. For Transistor power supplies. 
Pri. 200/240v. Sec. 9-0-9v. at SOOmA. 11/-. P. 4 P. 2/fi. 

MAINS TRANSFORMER. For transistor power supplies. 

Tapped pri 200-250v. Sec. 40-0-40 at 1 amp (with 

electrostatic screen) and 6.3v at .5 amp for dial lamps etc. 

Drop thro mounting. Stack size 1J" x 3J" x 3J" 27/6. 

P. 4 P. 4/6. 

SMOOTHING CONDENSER. 2800 mfd. 25v. 1J" dia. x 3" 

high 8/-. P. 4 P- 1/-. 

MATCHED PAIR OF 2} WATT TRANSISTOR DRIVER 

AND OUTPUT TRANSFORMERS. Stack size li x U x Sin. 

Output trans, tapped for 3 ohm and 15 ohm output. 

10/- pair plus 2/-. P. & P. 

7-10 watt OUTPUT TRANSFORMERS to match pair of 

ECL 86'8 in push-pull to 3 ohm output. ONLY 11/-. 

P. 4 P. 2/6. 

WELL-KNOWN MAKERS SURPLUS! 

ONE TRANSISTOR PRE-AMP 

Suitable for use with Medium or High Impedance mikes, 
guitars, gram pickups, tape decks etc; For operation from 
200/300 volt H.T. rail or 9 volt battery. Gain approx 14:1. 
Fully isolated input by Mu-Metal screened transformer. 
Size 42* x 1" x 1". Ready built complete with full circuit 
diagram and instructions. ONLY 15/-. Post free. 

Dual Purpose Bulk Tape Eraser and Tape Head Demacnet- 
iser, 35/-. P. & P. 3/-. 

TWIN TELESCOPIC AERIAL, Comprising two 3-section 
heavily chromed rods. Closed 12-in. each extending to 
32in. Completely adjustable from vertical to horizontal. 
Supplied complete with universal mounting bracket, 
coax lead and plug. Suitable for F.M. or TV. 12/6. 
P. & P. 2/6. 



SPECIAL HARVERSON OFFER! 

FM/AM TUNER HEAD 

Beautifully designed and 
precision engineered by 
Dormer and Wadsworth 
Ltd. Supplied ready fitted 
with twin .0005 tuning 
condenser for AM connec- 
tion. Prealigned FM sec- 
tion covers 86-102 Mc/s. 
l.F. output 10.7 Mc/s. 
Complete with ECC85 (0L12) valve and full circuit dia- 
gram of tuner head. Another special bulk purchase 
enables us to offer these at 27/6 each. P. 4 P. 3/-. Order 
quickly! Limited number also available with precision 
geared 3:1 reduction drive, 30/-. P. 4 P. 3/-. 

MATCHED PAIR AM/FM I.F.'s 

Comprising 1st l.F. and 2nd l.F. discriminator (465kc/s 
/10.7Mc/s). Size 1 x 1} x 2iin. high. WiU match above 
tuner head. 11/- pair. P. 4 P. 2/-. 




SPECIAL PURCHASE! TURRET TUNERS 

By famous maker. Brand new and unused. Complete 
with PCCS4 and PCF80 valves 34-38 Mc/s IF. Biscuits 
for Channel 1 to 5 and 8 and 9. Circuit diagram supplied. 
ONLY 25/- each. P. 4 P. 3/9. 



GORLER F.M. TUNER HEAD 

88-100, Mc/s 10.7 Mc/s I.F., 15/-, plus 2/- P. 4 P. (ECC85 
valve 8/6 extra). 

3-VALVE AUDIO AMPLIFIER 

MODEL HA34 

Designed for Hi-Fi repro- 
duction of records. A.C. 
Mains operation. Ready 
built on plated heavy gauge 
metal chassis, size 7Mii. w. 
x 4in. d. x 4}ln. h. Incor- 
porates ECC83, EL84, EZSO 
valves. Heavy duty, double 
wound mains transformer 
and output transformer matched for 3 ohm speaker, 
separate Bass, Treble and volume controls. Negative 
feedback line. Output 4.1 watts. Front panel can be 
detached and leads extended for remote mounting of 
controls. 

The HA34 has been specialty designed for us and our 
quantity order enables us to offer them p « c r\ 

complete with knobs, valves, etc., wired r.*r.O.U 

and tested for only P. 4 p. 1; -. 





HSL 'FOUR' AMPLIFIER KIT 

A.C. Mains 200/250v., 4 watt, using ECC83, EL84, EZ80 
valves. 

• Heavy duty double- 
wound mains transformer 
with electrostatic screen. 

• Separate Bass, Treble 
and Volume controls, giving 
fully variable boost and cut 
with minimum insertion loss. 

Heavy negative feedback 
loop over 2 stages ensures high 
itput at excellent quality 
with very low distortion factor. • Suitable for use with 
guitar, microphone or record player. • Provision for 
remote mounting of controls ordirect on chassis. • Chassis 
size only 7Jin. wide x 4in. deep. Overall height 4Mb. 
• All components and valves are brand new. • Very 
clear and conciseinstruct ions enableeventheinexperieiH'ed 
amateur to construct with 100% success. • Supplied 
complete with valves, output transformer (3 ohms only), 
screened lead, wire, nuts, bolts, solder, ete. (No extras to 
buy.) PRICE 79/6. P. 4 P. 6/-. 

Comprehensive circuit diagram, practical layout and 
parts list 2/6 (free with kit). 

This kit although similar in appearance to HAS4 employs 
entirely different and advanced circuitry. 



10/14 WATT HI-FI AMPLIFIER KIT 



A Stylishly fin- 
ished monaural 
amplifier with an 
output of 14 watts 
from 2 EL84s in 
push-pull. Super 
reproduction of 
both music and 
speech, with neg- 
ligible hum. Sep- 
arate inputs for 
mike and gram 
allow records and 
announcements to follow each other. Fully shrouded 
section wound output transformer to match 3-15 S2 
speaker and 2 independent volume controls, and separate 
bass and treble controls arc provided giving good lift and 
cut. Valve line-up 2 EL84s, BCC83, EF86, and EZSO 
rectifier. Simple instruction booklet 1/6. (Free with 
parts.) All parts sold separately. ONLY £7.9.6. P. & P. 
8/6. Also available ready built and tested complete with 
std. input sockets, £9.5.0. P. & P. 8/6. 
Carrying case for above 28/6. P. & P. 7/6. 




NEON A.C. MAINS INDICATOR. For panel mounting, cut 
outsize 1J x § x i'm. deep inc. terminal. White case with 
lens giving brighter light. For mains 200/250v. 2/6 each. 
P.P. 6d. (G or more post free). 



Open all day Saturday 
Early closing Wed. 1 p.m. 

A few minutes from Soitt?i Wimbledon 
Tithe Station. 



HARVERSON SURPLUS CO. LTD. 

170 HIGH ST., MERT0N, S.W.19 CHErrywood 3985 

SEND STAMPED ADDRESSED ENVELOPE WITH ALL ENQUIRIES 



(Please write clearly) 

PLEASE NOTE: P. & P. CHARGES 
QUOTED APPLY TO D.K. ONLY 
P. & P. ON OVERSEAS ORDERS 
CHARGED EXTRA. 



714 



AERIAL PROBLEMS 

SOLVED! 



The revolutionary JOYSTICK AERIAL SYSTEMS present a 
satisfactory solution to all the problems of restricted space receiving (and 
transmitting) aerials. A completely new range of tuning units have been 
designed to allow the maximum possible efficiency with absolute simplicity 
of tuning and operation. For reception on all amateur bands from 1.8 Mc/s 
to 30 Mas. for general short wave and broadcast reception including the 
medium wave band. This variable frequency aerial system has been acknow- 
ledged as the most successful solution to a host of aerial problems. Over 
10,000 are in use all over the world. Hundreds and hundreds of terrific 
testimonials may be seen at the Joystick Office. 

— — SWL JOHN D. THOMPSON SAYS: — - 
"Yesterday evening I was tuning in YV's on 15m. band 
with the HF tuner and later on switched round to the 
160m. band and a couple of GM stations rolled in like 
the home service. Frankly, I am astonished by the ability 
of the Joystick — surrounded as 1 am in a built up area — 
well within a town and in a valley with considerable hills 
around me". (JOYSTICK INDOORS!) 13 Old Park 
Road, Dover, Kent. 




Above: One of the new 
JOY MATCH 'EASY-TO-USE' 
units with built-in RF indicator 
for transmission 



OUTSTANDING SIGNALS FROM THE JOYSTICK VFA 
CAN BE HEARD EVERY DAY ON THE AMATEUR AND 
MARINE BANDS. 



UK AGENTS: G. W. Smith & Co. (Radio) Ltd.. 3 Lisle Street, London. W.C.2; 

Stephens-James Ltd.. 70 Priory Road. Liverpool 4; 

Chas. H. Young Ltd., 170/172 Corporation Street. Birmingham. 4; 

R.S.C (Manchester) Ltd.. 326 Argyle Street. Glasgow. C1; (and all branches) 

or ask your local dealer. 

France: Vareduc-Comimex, 2 Rue Joseph-Riviere, Paris. 
Courbevoie, France. 

Scandinavia: Permo. Nygaardsgaten 42, Fredrikstad, Norway. 
West Germany: Ing. Hannes Bauer, 86 Bamberg. Hornthalstrasse 8. 
Stotz & Goessl. 8 Munchen 15, Bayerstrasse 3. 

AND WORLD WIDE AGENCIES 

U.S. Patent No. 3274600 S. Africa Patent No. 83/4389. 

U.K. and World Patents applied (or. 



THIS BROCHURE GIVES YOU THE FACTS 
AND ONLY THE FACTS! 

SEND TODAY 

PARTRIDGE ELECTRONICS LTD. 

CAISTER HOUSE. PROSPECT ROAD, BR0A0STAIRS, KENT 



NAME 

ADDRESS 



CALL/BRS No 




PWA 



715 



SENSATIONAL COLLECTION OF BARGAINS 



NEW FULLY 
TRANSISTORISED 
PORTABLE RADIOS 

with Full Variable waveband. 
NOW A FRACTION OF THE 
NORMAL PRICE 



ONLY 



39/6 



WHY PAY MORE? All the 

latest refinements are packed 

Into till;, ii. w MVI.TI-STATIOS 

AL.LTranii-tiirm.lin- '.!. 

aerial pu .. 

Stallone and the powerful built-in 

speaker (rives room nillng volume. Individual tuning, 

m-st-cUss reception. Purchase with confidence — packed 

In original manufacturer's cnrfcins. (Perianal earpiece 

Md b att e r* ■■• 6> Bend 39/6 plus 4,tl p. * p. 



10 SEMI CONDUCTORS 

2 WAVEBAND 



Famous make 760 
only bought at 
it's below actual 
value 



in 



II • kno 
manufacturer}* carton- (who-e 
name we have agreed not to 
Latest 1967 mode! 
with multi-section 
telescopic aerial In addition 
to internal ferrite interceptor 
aerial. Thin full die 
nth in 100s of 
F.ngll.ih and I'.iiiimciitui 
stations. Works in int. 
plane or boat. Superb 
high flil. 

big speaker at half- 
filling volume. Once sold 
Mhlc price 
88/6 plus 4/6 carriage etc. (Leather 
case sling, earphone <te battery 9/6 
;, (bum 
try at homo for 7 <i.i\ -. 





han.l 
97/6 



Miraculous Scoop from 
Swiss Manufacturer 
Limited Shipment NEW 
21 JEWELLED 
DIVER'S WATCH 

with Itotating Timing Bezel. 
Staggering price reduction — 
compare prices Q"7 / A 

locally. 950 only it «*'/w 
■Take ;. genuine I 
CASH SAVING on this high- 
watch, -Jni) vacunm 
for dcplli. SI .Tcwelle.l 
i.:. Shoek-pfOQfg elec- 
tronicaU] timed, lum. dial and 
uHng. motoring, 

plus 4/6 p. & r. PB81 M BOMB. Mown back 
12/8 extra. 




SAVE YOUR LEGS! 
INTERCOM OUTFIT 

& BABY ALARM 
Ready Built 

Only 4QJ6 






Robustly made, brand 

new »•:' 

at 1 

( r.m- . ' 
.111 rn ii i. 

i: to the other — 

complete with mm. 

wire. Fixed in a flash. Ends Iraly crytng 

rkahop t.. Hon* 

mil ..i stands up. Our price 49/6. 

ex. Post. etc. 4/6. Money back guarantee. 



Profit from the credit squeeze! 
Importers stock bought at miles 

below actual value 
4 TURRET SUPER 500X 
POWER MICROSCOPE 
only 39/6 

not a penny more to pay. Full size 
9' high— don't couluse with 
miniatures. Grade A.l all metal 
construct ion in Mack cm. 
plated parts. Accurate rack and 
pinion focusing giving crystal 
clcarilellrntli.il. ; optical: : 

■■'. giving 
lOOx, 200x. 300x and oOOx. Magnifi- 
cation powers. AiftaUMt mirror 
light reflector and tilting Joint. 
[deal tor home, bobbyisl 
study, etc Brand new in box 
ufaiijili In "iih lUda m /reeffoa «/ 
U ONLY 39/6 plus 4/6 
post, carriage, etc. Money back a'lee. 




Frustrated Import 
Shipment 
OFFERED BELOW 
HALF PRICE 
TO CLEAR 500 only 

5 TRANSISTOR 

PERSONAL TRANS- 
CEIVER SETS 



PRICE 
You've heard almnt them— You've read about them. 
ROW'S VOI.K CHANGE To OWN THEM. Highly 
-•■h-ltive two-way tran-i-t'T tr.tn-eelver seta have 
individual volume control and talk-listen switch. Tclcs- 

ftel pulls In the mil.' ir-mi the ..the) 
tremendous distances — no wires — a genuine bnm 
a- ii-. .1 hy official bodies and forces. 300 sets only at 
£6.19.6 plus 5(0 p. .V p. (BattirleK, leather cases, etc. 
10/6 extra). Money back If not delighted with the per- 
. These eannnt lie operated In U.K. 




3500 Bought at "Rock Bottom" Off 
Leading British Maker 

^■fe^Skt- > REAL EPISCOPE 

^2%%h J^kV^K PROJECTOR 




ONLY 



45/- 




to pay! Project- FULL 

8IZE Magnitied PICTURE onto 

rata «nfl ,.i screen m BLACK & 

WHITE OR COLOUR with CRYSTAL CLARITY ANY 

PHOTOGRAPH. DOCUMENT, picture drawing, stamp 

il — hu ndreds of use* in 

hooboom, oto. A FULL SIZE precision 

made sclciilillc Instrument WITH REAL GLASS REFLEX 

LENS. Slued;. reUsWC, Bo -in.pl. even I child can 

-tan.lar.l main- BRAND NEW pomp 

eabta, bans, ate. Qfftni si fraction i>/ real north ui 45/- plui 

/',./'-. -v I'ltrl.. 

This is truly a wonder 
purchase. Limited quantity 
only of FABULOUS EVER- 
GOLD POCKETWATCHES 

Now at the lowest ever 
price. ONLYOC/ 

No More To Pay*—sJ/~ 

Now offered at well below clearance 

1 these remarkably reliable 

BVBBGOLD pocket watches. 

Desigin-.i to withstand yean of wmBta.nl me with inch 
unbreakable | talking* 

aoaaayl I glanee.Fulry guaranteed 

DON I HIBe THIS ONCE Ui v LIFETIME BARGAIN 
Bend onrj BS'-pms i t t * P fa : day»' free home trial. 
jfenef Me* »•/ now '.■••' •'•■. tartato 

2,000 only being cleared regardless of loss 
because of over production 
MAKE YOUR 
ELECTRIC DRILL 
3 SPEED WITH 
THIS RIGHT ANGLE 
VARIABLE DRIVE 

Mounts directly on to your drill spindle 

or chuck in seconds. Doubles or halves 

For only the speed of drill. Allows larger bits 

Oat IC to be used. Make- metal, masonry 

/H/tl drilling cH.-ler. Ka-v-crlp handle attache.' 

■—•*/ *• to .i'Ii- I 

drill for work of a inachlor costing ten times the price! 
Brand new in makers' carton. 2.000 only at 29/6 plus 
,'i/li P. A P. M"lic> Lack iruaranle... 



Make 5 different 
TRANSISTOR 
RADIOS for 





39J6 



No 

Experience 

Necessary 

No soldering. Only B eon- 
tar nr-i radio 
to wnrk. Ju-i I 

1 lay ABC Plans, 
[KQSS ■ <?t? /$> Loudspeaker 

"*^<S>,<f, '*r lalone 17/6). Barphone, 4 Semi- 
■ ta nrjarjaara 
Resfanor*, Timer. ftwit.h. Serein, ate, YES-EVERY 
THING: Load I IMf English and Foreign reception. As 
supplied Authorities, li.M. Forces, etc. 

TESTlMONIALa OALORB. Oomplata ommm nrigmnttj 
£8, Sow only 39/6 plus 4») Post etc. 



NO SOLDERING 

AMAZING 

CIGARETTE 

RADIO 



ONLY 



25/- 



Yes a perleotly ordinary 
packet ol cigarettes: lint 



■ten 







(etch in 

station, load and dear) BUD hold- in cigar. 
cleverly corneal- highly senatUve, full) tr.in-i-t..rl--.l . li- 
e-nil (including battery), liven a young boj ran u«- 
seiuble it under 2 h.nir-. No soldering. No experience 
necessary. Only 16 connections to make. Ideal I 
to work urn. fan. Prom our bulging, teatim i 
Br. D. B. of Huddorsneld, writes: ",,,/lai «W»d "■• 
parts In il anil il U w ar M wo leouderfullu . . . " All. !■ IRTB 
Including Beml-Conductora. ABC Plans, ate. ONLY 25/- 
plos2/6 post, etc. I'ait> Available Scpatautu. 

Test this SELF-WINDING WATCH 

on your wrist lor 7 days FREE: 

1,000 purchased at mile- below 

actual value. Otrr amazing 

ft "1 C 

YOD NEVER WIND IT 
■ Famon- Timotviy |]|| 

juitiinate in Bwiaa anton 
'Unbeatable 

1967 tlei.C- Slimline'.'! 
diamond tooled, air 
date-change, imlueakal.le 

nialn-|iriiig, waterpni • 

• lly timed, luxurious 
gold finish, screw liaek, 

iBaadi ■aookproofi 

Iliathematkal hairipr.'. 
tiiieaiiny aecuracy. Bran i 
new with linaiaiii.-e. Send 
acelel it 6 ex.). [or trial— 
i lull without question, il not delighted'. 

NEW RADIO No soldering 

VOLKSRADIO 

ANYONE CAN BUILD 
IN 2-3 HOURS 

ONLY 




251- 




EVEN THE OLDER 
CHILDREN BUILD 
THEM! . . . no solder- 
ing ..nly 16 eonnce- 
I hen hear it 
reach out bringing in 
station aftei station, load and clear. Palm-of-haml rtte 
onlab: M.H. o! Bradiord 
writes: " . . . / •«« )■!»/ roni,ileted one of your HU 
fully. II il the flrll lime I Urn. 

radio, nnil I RIM I eased A""' 

easy It I* la •> lui/nm.. JUtt me* lour tMsi 

eartftttta Utattyil attf ... thai nan 
the niori i " Direct from Manufac- 

turers to You. Send 25/- pins 3/6 post. etc. 

PARTS AVAILABLE BBPARATKZT. 




Scoop purchase, save ££s 
NEW DOUBLE LENS 
REFLEX CAMERA 

0NLV 19/6^ 

You'll never get another bargain 

like tins: purchase 

Irani dhUemed Importer ottered 

at iraction of real worth — unrepeat- , 

able once this batch is sold. Pall -'.: 

doable lens reflex camera that eve 

a child can use. Take- 12 full sUe 

127 pletm.- ii Full colour or 

black/white. You'll marvel at your 

prolessional pictures. hVautlfu!l> made and Itnlshi 

size 4j I n. high nun. high with iocusini 

■Id but I 
lifetime, ltraud new in maker;, cat tuna— our give- 
away price 19/6 pins 9/fl p. « p. 

I. „.l..al.l,-dly ;m hne.1 er,r Itadlo Offer. 

9 TRANSISTOR 
A.M./F.M. 

Crazy price ONLY 
£7.10.0 

We invite yon to test ill 

at home ior 7 days &i 

guarantee your money ( 

back in full il not 100"., 

delighted. This PULL 

SIZE Electronic Marvel 

pulls in private broadcasts and 

interesting stations y.m wtralm 

dream of getting ptas K.B.C., IMS., Piiatl 

and Contmcntafa Thi 

aerial ensures finest directional reception in all 

i il .niality aud tone, mnplcl »ilh it- high 

sensitivity tuning, gnarantew perfect a&trtty. fully 

GUARANTEED. Don'l nu-- this limited period 

Send £7.10.0 lor 7 days' home test plus 5/6 p. & p. i Leather 

carrying case, aarpleoei batteries, etc., 8,6 extra.) 




CONCORD ELECTRONICS LIMITED 



(P.W.36) 87-89 TABERNACLE ST., LONDON. E.C.2. 

CALLERS WELCOME-DEMONSTRATIONS DAILY 



716 




QUALITY 



/SIP 




ANOTHER CODAR TRIUMPH! 



THE CR.70A COMMUNICATION RECEIVER. 

This completely new receiver sets a new high standard for 
performance and finish unequalled at the price, and Is a worthy 
addition to the outstanding range of CODAR quality communi- 
cation equipment. Frequency range: 560 Kc/s-30 Mc/s (540-10 
metres) In four ranges: 560 Kc/s-1.5 Mc/s; 1.5 Mc/s-4.2 Mc/s; 
4.2 Mc/s-11.5 Mc/s: 11,5 Mc/s-30 Mc/s. Slide rule scales for each 
band calibrated in frequencies plus an additional logging 
scale In degrees. Two speed vernier timing control with reverse 
slow tune action. Unique aerial Input stage exclusive to the 
CR.70A employing High 'Q' Air-spaced COD AK-COIL Inductor 
giving extremely high gain with low noise level. Panel aerial 
trimmer for peaking weak signals. Double tuned I.F. Iron 
cored transformers. 470 Kc/s with EF183 frame grid valve lor 
maximum gain and selectivity. 5 valves (including two twin 
triodes) giving 7 valve line-up. Separate B.F.O. stage forCWand 
SSB reception. Calibrated signal strength 'S' meter, illumin- 
ated. Automatic Volume control. Panel phone Jack for 'private' 
listening. 2-3 ohm output for external speaker. ( Matching unit 
optional extra.) Superb styling, metal cabinet in the new 
Organasol Satin lustre finish. Size: 13' x 5!" x 7{". For A.C. 
200/250V Ready built. Not a Kit at the fantastic low price of 

£1 9.10.0. Can-. 7/6. 

CODAR R.F. PRE-SELECTOR MODEL IM1.30. Consider- 
ably improves the performance of any superhet receiver over 
1.5-30 Mc/s. Uses EF183 Frame Grid Valve, and provides up to 
20dB gain plus substantial image rejection. Improved signal/ 
noise ratio and selectivity. Selector switch for either dipole or 
single wire antenna. Power requirements 180-250 volts 12mA 
H-T.6.3 volts. .3ampL.T. SlzeSJ x5x4in. Ready built, complete 
with cables, plugs and instructions. £3.10.0. Carr. 4/6. MODEL 
r.i:.::"X. Self powered model for 200-250v. A.C. Also provides 
25mA at 200v. H.T. and 6.3v. 1 amp L.T. for other accessories 

£7.4.0. C arr. 4/6. 

CODAR •■if MULTIPLIER MODEL R.Q.I0. For use with 
any superhet receiver with an I.F. between 450 and 470 Kc/s. 
Provides considerable increase in selectivity for either peaking 
or rejecting a signal on AM. CW. or SSB. BFO. Size 81 x 5 x 4in. 
Power requirements 180-250v. H.T. at 5mA 6.3v. .3 amp L.T. 
R«ady built complete with cables, plugs and Instructions. 
£6-15.0. Carr. 4/6. MODEL R.O.inx. Self powered version for 
200-250V. A.C. and also provides 25mA at 200v. H.T. and 6.3v. I 

a mp, L . T. fo r other accessories £8.8.0. Ca rr iage 4/6. 

CODAR A.l.'i. i; WATT 2 BAND TRANSMITTER. The 

newest most compact transmitter ror fixed or mobile use on 
160-80 metres. "The tiny TX with the BIG voice". Size only 
81 x 5 x 4in. (Base area is less than two-thirds of this page!) 
High stability new type calibrated VFO. L8-2.0 Mc/s and 3.5-3.8 
Mc/s (up to 4 Mc/s export). Air-spaced CODAR COIL Pi-net 
output. P.A. Plate current meter plus neon Indicator. Plate- 
Screen modulator. AM/CW switch and Panel key jack. Plug 
change over for 6 or 12 volts healer supply. Ready built £16.10.0. 
Carr. 4/6. A.T..'. POWER SI IMMA I MIS. For 200-250V. A.C. 
and I2v. Solid state for Mobile use, complete with all Transmit/ 

Receive changeover switching availab le. 

( llll \It-KII lli.liK MAINS T.R.F. SHORT-WAVE RE- 
CEIVER. World wide reception— North and South America, 
Russia. India. Australia. Far East. Amateurs, Shipping, etc. 
••Separate electrical bandspread. * 3 slow motion vernier 
drives. * Low loss polystyrene plug-in coils, factory aligned 
■Jr Dials calibrated In frequencies and degrees. * Power output 
3 watts for 2/3 ohm speaker. * Valve line-up: ECC81, EL84, 
E&80. Size 12 x 5J x 7in. CODAR-KTT CR.45K complete with 
valves. 3 colls (10-28, 25-75, 60-176 metres) and 11 page Instruction 
manual. £9.10.0. Carr. 6/-. Extra coils 5/- each. Instruction 
manual only 4/- (credited on order). (Can also be supplied ready 

built— price on reques t). i 

CODAR-KTT MIM-CLIPI'ER— OUR FAMOUS SHORT- 
WAVE it IX E1VER * Can be built in one evening ready to 
switch on and bring the World to your fingertips at very low 
cost. * Supplied complete with valve, one coil 25-75 metres 
and 4-page Instruction manual. PRICE 39/6. Can-. 3/-. Extra 
coils 51- each. Instruction manual only 2/- (credited on order). 
Electrical bandspread available. Provision to add 2 transistor 
' amplifier. 



Send 6d. in stamps for illustrated leaflets of the Codar range 




H.P. terms available • World-Wide Mail Order Service 

CODAR RADIO COMPANY 

BANK HOUSE, SOUTHWICKSQUARE 
S0UTHWICK. SUSSEX. Tel. 3149 

G3IRE G3HGQ 

Canada: Codar Radio of Canada. Tweed. Ontario 



717 




VIKING TRANSISTOR 

40-50 WATT AMPLIFIER 

OPERATING INSTRUCTIONS 
GENERAL. An extremely re- 
liable lightweight amplifier cap- 
able of giving 40-50 watts of 
iindistorted sound, made poss- 
ible by the use of the latest 
semi-conductors (transistors) 
and techniques which ensure 
space-age reliability under the 
most rugged conditions. It is 
designed as a general purpose amplifier particularly suitable for use with 
musical instruments that require exceptionally hiyh treble response (not 
recommended for Bass Guitar). Tremolo facilities are available on Channel 
1 only. INPUTS— CONTROLS— CHANNEL I (Tremolo): this contains 
two high gain input jack sockets controlled by Volume Control 1 which is 
mounted directly above the two sockets marked tremolo. BASS 1 : gives 
a controlled boost to the lower frequencies on Channel 1 only. TREBLE 
1 : gives a controlled boost to the high frequencies on Channel 1 only. 
TREMOLO: this operates on Channel 1 only and the variations of inten- 
sity and speed of the Tremolo beat is adjusted by the controls DEPTH 
and SPEED. A socket is provided in the rear of the amplifier so that the 
Tremolo may be switched on and off by the use of a footswitch plugged 
into the socket. If you wish the Tremolo to be used without the foot- 
switch, this is possible as the footswitch is only used to short out the 
effect. INPUTS AND CONTROLS CHANNEL 2 (Normal): this 
contains two high gain input jack sockets controlled by Volume Control 2 
which is mounted directly above the sockets marked Normal. TREBLE: 
gives a controlled boost to the treble frequencies on Channel i only. 
MAINS VOLTAGE: fullv adjustable. 2OO-260 volts, A.C. 50 cvcles. 
POWER OUTPUT: 40-50 watts sine, wave British rating. Very little 
distortion. OUTPUT IMPEDANCE: :! ohms. Price 21 gns. plus £1 
postage and packing. 

WOLSEY U.H.I-. AERIAL AMPLIFIER, two stage, gain 2:i db. noise 
factor S db, power consumption fi ni/a at 14 volts. Two AF186 tran- 
sistors, complete with built-in power supply in metal case, list price 

9 gns., our price 4i gns. plus 2/ii postage and packing. 

MAINS TRANSFORMER, primacy 200/250 volt, secondary 425/425 
volt. 250 mA, 6.3 volt 4 amp, 5 volt :{ amp; fully shrouded, chassis 
mounting. Price £2.5.0 plus 7/6 postage and packing. Auto transformer 
step-up-step-down, 240/110 volt 400 watt. Price £1.5.0 plus 7/(1 postage 

and packing. 

MAINS TRANSFORMER 200/250 volt, secondary 250/25O volt, 70 mA. 
6.3 volt, 3 amp drop through. Price 12/6 plus 4/ii postage and packing. 
Elac 10 inch, 10,000 lines ceramic magnet, 3 or 15 ohms, 7 watt, £1.9.6 
plus 4/6 postage and packing. 



POCKET MULTI-METER 

m.- ■■: x j: x ljin. Meter size 2J x liin. Sensitivity 1000 
O.I'.V. on both A.C. and D.C. volts. 016. 0150 0-1000. 
D.C. current 0-l50mA. Resistance O-IOOkO. Complete 
with test prods, battery and (all instruction*. 48/6. P. * P. 
3/6. FREE GIFT (or limited period only. 30 watt Electric 
Soldering Iron value 15/- to every purchaser of the Pocket 
Multi-Meter. 




Twin 40W Choke instant start 



40W FLUORESCENT LIGHT KIT 

Incorporating GEC Choke size 81ln. X liin. x ljin . 
2 hi-pin holders, -1 1 /c 

starter and startei-holdcr. P .4" P. 5/6. I I /© 

Similar to above: SOW. Fluorescent Light Kit In- 
corporating GEC choke -i/..' ii;>n. t i;m 
2 bi-pin holders, start ami starter holder.' 
P. & P. 0/6 
for 2 X 2ft tubes 17/6. P. 4 P. 5/6. 




17/6 



I MUSETTE %sr portable radio j 



39'6 



MULTIPLEX DECODER 




• 2J ' Speaker. 

• G Transistors 8uperhct Output 2(l0mW. 

• Plastic Cabinet In red, size 4 {* x 3" x I |" 
and gold speaker louvre. 

• Horizontal Tuning Scale. 

• Ferrite Rod Internal Aerial. 

• IF 470 kc. 



P.1P. 3/6. 
Circuit diagram 2/6. 
Free with parts. 



INCLUDING CARRYING STRAP 

• All components. Ferrite Rod and Tun- 
ing Assembly mount on printed board. 

• Operated from PP3 Battery. 

• Full comprehensive instructions and 
point-to-point wiring diagram. 

• Printed Circuit Board. 

• Tunable over medium and long wave- 
band. Car aerial and ear piece socket. 



For receiving Stereo FM 

Now Is your chance to benellt In full from the 
in m B B.C. stereo transmissions with our 
Multiplex Decoder. Design features: Highly 
efficient Milliard vinkor pot cores. Two semi- 
conductor diodes. Double purpose valve. 
Printed olranll type construction high Input 
Impedance Specification: cross talk tamos 
20 iiit m l kc>. uiput requirements 0'fi — 1 - 5 
RMS. Stability phis M minus U-1%. Voltage 
requirements 11. T. 190— MO volts. D,C. at 5 

mA. beaten B«8 volts. A.c. at aoo mA. BeH 

powered unit shortly available, price to be 
announced. Size BJ" x 35" x 1". Fully built 

and tested. 




Price £4.4.0 P. & P. 3/- 




Type E MOTOR 



-small A.C. mains motor 3304250 volts 
complet »- with gearbox. 6 r.p.m. Price 
15/- plus 4/-. P. 4 P. 
Similur to above motor but without 
gearbox. Price 9/6 plus 3/-. P. 4 P. 




FIRST QUALITY P.V.C. TAPE 



5Jin. Std. 850ft. 

Tin. Std. 1200ft. 

Bin. L.P. 240ft. 

5,'ln. I..P. 1200ft. 

7iu. I..P. 1800ft. 

5Jin. D.P. 1800ft. 
P. 4 P. on 



9/- oln. L.P. 850ft. 

11/6 Sin. T.P. 000ft. 

4/- 5in. T.P. 1800ft. 

11/8 5?in. T.P. 2400ft. 

18/6 Tin. T.P. 3600ft. 

18/6 4iu. T.P. 900ft. 

eh 1/6, 4 or more post free. 



10/6 
10/6 
25/6 
32/6 
42/6 
15/- 




"MAYFAIR" 5-Transistor 

TAPE RECORDER 



Capstan-driven, battery operated 71 and 3J i.p.3. 
Precision made. Push-button controls. High 
quality 2|in. speaker. Push-pull circuit. Output 
•JOOmW. Frequency response: 200-7.000 kc/s. 
Fast rewind. Up to 1 hour twin track playing 
time. Automatic erasing for re-recording. Dimen- 
sions: Sin. x liin. x 3|in. Weighs only 71b. Takes 

£11.11.0 plus 9 -P. 4 P. 



SILICON RECTIFIERS 

Kfl v. P.l.V. 750 milliamps. Six for 7/6 postpaid. 



3 to 4 WATT 

AMPLIFIER 

3-4 watt Amplifier built and tested. Chassis size 7 x 3i x 

llu. Separate l>ass, treble and volume control. Double 

wound mams transformer, metal raetifier and output 

transformer for 3 ohms speaker. Valves ECC81 and 6V6. 

£2.0.0 plus 5/6 p. 4 p. 

The above hi Kit Form. 29/6 pin- 5/ii p. .* p. 

8" x 5" speaker to milt 14 '6 plus p. 4 p. 1/6 




POWER SUPPLY KIT 

A.C. MAINS 200— 250V 

Incorporating "C" core type mains 
transformer, full wave metal rectifica- 
tion and smoothing condenser. Smooth 
output 250 v. 250 mA and 
6-3 v. 4 amp. lor Heaters. 

~ & P. 



25/- 




NEW TRANSISTORISED 
SIGNAL GENERATOR 

Size 51" X 3i" x If. For IF and RF 
alignment and AF output 700 c/s fre- 
quency coverage 460 kc/s to 2 mc/s In 
switched frequencies. Ideal 'or align- 
ment to our Elegant Seven and Musette. 
Built and tested. «q in 

Oy/O p. & p, 3/6 



CYLDOIM 
U.H.F. TUNER 

Complete with PC88 and PC86 
Valves. Full variable tuning. 
New and unused. Size 15 s 5} x 
ljin. Complete with circuit 
diagram. 5K l_ P""* 3/6 



35/- 




• ALL ORDERS BY POST MUST BE 
SENT TO OUR ACTON ADDRESS 



RADIO & TV COMPONENTS (acton) LTD 

21 C HIGH STREET ■ ACTON ■ LONDON ■ W.3 



•fr Our new branch at 

323 EDGWARE ROAD, LONDON, W.2. 

IS NOW OPEN • PERSONAL SHOPPERS ONLY 

ALL ENQUIRIES STAMPED ADDRESSED ENVELOPE 

OPEN 9 a.m.— 6 p.m. INCLUDING SATS. EARLY CLOSING WED. 
GOODS NOT DESPATCHED OUTSIDE U.K. TERMS C.W.O. 



718 



***^f Mkll ^ 



SPECIAL OFFER 

7" x 4" P.M. Speaker at no extra charge 

Buy yoursell an easy to build 7 transistor radio and save at least £10.0.0. Now 
you can build this superb 7 transistor superhet radio for under £4.10.0. No one 
else can offer such a fantastic radio with so many de luxe star features. 

* De luxe grey wooden cabinet size 12i" x SJ" x 3i". 

•k Horizontal easy to read tuning scale printed grey with black letters, 
si2e 11J" »2". 

* High 'Q' ferrite rod aerial. 

* I.F. neutralization on each separate stage. 
•k D.C. coupled push pull output stage with 

separate A.C. negative feedback. 

* Room filling output 350 mW. 

* Ready etched and drilled printed circuit 
board back printed for fool proof 
construction. 

■k Fully comprehensive Instructions and point-to-point 
wiring diagrams. 

■At Car aerial socket. 

ie Fully tunable over medium and long wave. 16&-535 metres 
and 1250-2000 metres. 

■*■ All components terrlte rod and tuning assembly mount on 

printed board. 
tt Full after sales service. 

* Parts list and clrcuil diagram 2s. 6d., free with parts. 



COMBINED PORTABLE *w 

CAR RADIO 



ONLY 



£4.4.0 

Plus 7'6 P. & P. Parts List and 
circuit diagram 2'6 FREE with 
parts. 



To purchasers of 'Elegant 
Seven' parts, incorporating 
mains transformer, rectifier 
and smoothing condenser. 
A.C. mains 200/250 volts. 
Output 9v 100mA. 7s. 6d. 
extra. 




RADIO & TV COMPONENTS (acton) LTD 

21 C HIGH STREET ■ ACTON ■ LONDON ■ W.3 



*0ur new branch at 

■ 323 EDGWARE ROAD, LONDON, UU.2 

IS MOW OPEN 

PERSONAL SHOPPERS ONLY 



ALL ENQUIRIES STAMPED ADDRESSED ENVELOPE 

OPEN a a.m.— 6 p.m. INCLUDING SATS. EARLY CLOSING WED. 
GOODS NOT DESPATCHED OUTSIDE U.K. TERMS C.W.O. 




MMMl 




The New 1 Picture -Book way of learning 

ELECTRICITY C5 Vols) 

ELECTRONICS [6 Vols] 
ELECTRONIC CIRCUITS (2Vols) 
INDUSTRIAL ELECTRICITY [2 Vols] 
SYNCHROS & SERVOMECHANISMS [2 Vols] 




HD 



lJJ 



You'll ttnd it easy to learn with this outstan.llngly successful 
new pictorial method— the essential facts are explained in 
the Simplest language, one at a lime: and each Is illustrated 
by an accurate cartouu-type drawing. 



The hooks are based on the latest research into simplified 
learning techniques. This has proved that the Pictorial 
Approach to learning is the quickest and soundest way of 
gaining mastery over these subject*. 



series will be of 
exceptional value in 
training mechanics and 
technicians in electricity, 
Radio and Electronics. ' 



WHAT THIS MONTH'S ENTHUSIASTIC 
READERS SAY 

"/ A.i.. rtCtHtlm htiri rl„ plmUttn of penning your excellent publica- 
tion* on BASIC ELECTRICITY and BASIC ELECTRONICS. 

teltteli are UK ueailahle from our I1IXZAF) Service libraries . . ." 
O.W.K., New Zealand. 

"', ,'"".'' •*"""' BA8I0 ELECTRICITY and BASIC ELEC- 
TRON IVS erceUrnl publications and look for tea rd lo future 
publications us available . . ." P.J.T., Blackburn. 



POST NOW FORTH/S OFFER! 



TO SELRAY BOOK CO. 
60 HAYES HILL, HAYES, BROMLEY, KENT 

?£ ase r? cn< L me Wilhout Obligation to Purchase, one of the above sets on 
7 Days Free Trial. I will either return set, carriage paid, in good condition within 7 days 
or send the tollowmg amounts. Basic Electricity 70'- Cash price or Down Payment of 
15'- followed by 4 fortnightly payments of 15'- each. Basic Electronics 82'- Cash Price 
or Down Payment of 15'- followed by 5 fortnightly payments of 15'- each. This offer 
applies to UNITED KINGDOM ONLY. 

Tick set required (only OXE set allowed on free trial). 

BASIC ELECTRICITY 70'- H BASIC ELECTRONICS 82'- n 

BASIC ELECTRONIC CIRCUITS 40'- n 

BASIC INDUSTRIAL ELECTRICITY 40'- 
BASIC SYNCHROS & SERVOMECHANISMS 38'- [ 
ALL PRICES INCLUDE POSTAGE 

Signature 

(If under 21, signature of parent or guardian) 
NAME 

FULL POSTAL ' ' ""* ™"*** »«*» 

ADDRESS 



719 



TRS 



BARGAINS in Modern Quality 
Kits, Components and Equipment 



TRS FM STEREO DECODER 

OUTSTANDING T.R.S. VALUE 

Based on Milliard's proven circuitry, this is a six transistor, printed 
circuit unit size o'i x BJiQ. Two stage transistor Stereo Beacon 
Indicator is incorporated. Operates from I2v. supply. Nejj. earth. 
Basic Kit supplied suitable for Transistor Tuner input and Transistor 
Amplifier output. With simple mods (data supplied with Kit) the unit 
is easily adapted for Valve Tuners and Valve Amplifiers. Kit and 
assembly instructions, complete with Milliard specified Inductors, 
Tvpe WF2949 and WT2951. 

Complete kit ^ With coils tested 

as described CA_ 1Q K and pre-aliK'ncd f R h h 

LHi lu.U Carnage either kit 2/6. LJ.J.U 



FM DECODER COILS 

Designed and made by Mullard. the.se 
Inductors are as used in T.it.S. 
Decoder above. TYPE WF2949 and 
■WF2981, each 85/-. Per pair 49/6. 
post free. 



MISCELLANEOUS 

ENAMELLED COPPER WIRE- 9 oz. reel* 
14 g.-20 g. 3/-; 22 g.-28 fr. 3/6; 30 g.-S4 g. 
4/3; 36 g.-S8 g. 4/9; 39 g.-40 g. 5/-. etc. 
TINNED COPPER WIRE, 16-22g. 4/- 2 oz. 
BONDACODST Speaker Cabinet Acoustic 
Wadding (1" thick approx.') IS" wide, any 
lencth cut, 6/- yd. 

VEROBOARD — All sizes including 24 In. x 
5m. 3/8; 24_m. x 3Jln., 3/-; 3|m. v Sin., 
5/2; SJin. x 3*in., 3/8; 3im. x 171n.. 12/8. 
All accessories and tools in stock. 
VOLUME CONTROLS. LOO and LINEAR 
— 5K-2 MO 31n. Spindle* Morgana e 
Midget Type ljm. diam. Guar. 1 year. 
LOG or LIN ratios less Sw.. 3/6. DP. 
Sw. 5/-. Twin Stereo less Sw., 7/6. DP. 3w„ 
9/6 (100k to 2 Meg. only). 
RESISTORS -Modern ratings lull range 10 
ohms to 10 megohms 20% ;-! ir, 3d. ea.. 
ditto 1 »., 6d. ea., 2 w, 9& ea., 10 
4d. ea., 5% Hi-slab., 1-1 w., Bd. ea. (Iielnw 
100 ohms and over 1 meg., 9d. ea.). 1% 
Hl-stab., { w., 1/6 ea. (below 100 ohms, 
8/- ea.). 

ERSIN MULTICORE SOLDER. 60 4(1 4d. 
per vard. Carton? 6d., 1/-. 2/8 etc. 
WIREWOUND RES1STOR8. 25 ohm to 
10 K. 5 w. 1/3. 10 w. 1/6. 15 w. 8/-. CON- 
DENSERS Silver Mica. All values 2 pi. to 
1.000 pi. 6d. ea. Ditto ceramic. 9d. Tub. 450 
v. T.C.C., ete. .001 mid to .01 lOd. and 
.1 '350 v. lOd. .02 MF to 0.1 MF. 5U0 v. 1/-. 
.86 T.C.C. 1/9. .5 T.C.C. 2/-. 
CLOSE TOL. S/M1CAS. 10% 6 pf. 500 pf. 
9d. 600-5,000 pf. 1/-. 1% 2 pf-100 pf. lid. 
100 pf.-250 pf. 1/2. 270 pL-800 pf. 1/4. 
800 pf.-5,000 pf. 2/-. 

ALTJMTN. CHASSIS. 18g. Plain uudrilled 
folded 4 Bides, 2in. deep. Bin. x 4in., 4/6; 
Sin. x 6m., 5/9; lOin. x Tin., 8/9; 12m. x 
6in., 7/6; 12in. x 81n.. 8/- etc. 
ALTJMIN. SHEET. lSg. 6tn. x 6in. 1/-; 
6in. x 9in., 1/6; 6in. X 12in., 8/-; 12in. x 
12in., 4/- each. 

TYGAN FRET (Content, pat.) tSfa. x I2in.. 
8/-;12in.x 18in. 3/-; 12lu. x 24in., 4/-otc 
FOSTER DYNAMIC MIKE. 600 Ohm 
Impedance. Complete with Desk atand, 
Leads etc. A neat Hi quality Unit. 59/6. 
Also High L-npcdance (50K). 69/6. 
CONTINENTAL SWITCHED — Popular 
Stick Type. High Imp., 42/6. 
SUPERIOR CONTINENTAL DE-LUXE 
STICK MIKE WITH SWITCH. Neck Cord 
suspension. Stand adaptor and Base. 
Black and Chrome finish. Complete with 
plug-In Lead and neat presentation box, 
59/6. 

MICROPHONE INSERTS. 
ACOS XTAL Type MIC 14 IJin. x Jin. 
7/6. MIC 43 13in.x 5 / la in., 8/6. Continental 
type tin. x jln., 6/-. 



A UNIQUE TRANSFORMER 
SERVICE 

WemanufactureTransformers 
and Chokes of all types. 
Enquiries invited for Protos 
and small runs. 



6 VALVE AM/FM 
TUNER UNIT 




In Kit Form with or without Power Pack 
Med 196 tn.. 650 m., V.H.F.- Bfl M. 
103 Mc/a, 6 valves and metal rectifier, 
Self-contained power unit. Magic-eye, 
3 pu«h-button controls on/off, Med., 
V HI". Diodes and high output sockets 
with gain control. Illuminated 2-eoloiir 
perspex dial 11 Jin. x 4in. Chassis slxe 
lUii x 4in. x 5}ln. Strongly recom- 
mended fur use with Mullard amplifiers 
below. For A.C. mains 200/250 v. Un- 
beatable value. Complete kit. Inc. Power 
Pack as Illustrated, 11 ens. Carr. 7/6. 
1 litt.. let* Power Pack, 10 KM. Carr. 7/6. 
Circuit and Const, details 4/6. Free 
with kit. 



MAKE YOUR OWN INSTANT 
CIRCUITS WITH "CIR-KIT" 

Enables yoa to produce "prints! <'«r<iili-" 
quickly ami cleanly without chemical or 
elaborate processes. Kit No. 3 inr. 
baseboard, processed copper * trip 
I as advertised. 



15/- 



TAPE BARGAINS 

ISOOIt.. ?in. REEL. American ptofta- 
sional quality tape. Gives 1 J hrs. playing 
per track at SJ r.p-s. With leader and 
stop foils. In' attractively presented 
sealed boxes. Ideal for 2 and 4 track 
machines, mono or stereo. Outstanding 
value at 17/8 per reel (p/p 1/- for first 
reel, 6d. each after first when ordered 



UNIQUE DOUBLE SIDED TAPE on 
ojin. reels. Superb quality used In 
normal way. Ideal (or experimenters too. 
660ft. 9/-. OOOIt. 8/8. (P/p 1/- pet single 
reel. Bd. for each additional). 
EMPTY TAPE KEELS (Plastic). 
An. 1/3. tta. 8/-. 5in. 8/-, 5jin. 8/-. 
Tin. 8/8. 

PLASTIC REEL CONTAINERS 
(Cassettes) Sin. 1/8. 6in. 1/9, BJin. 8/-. 
71n. 8/3. 



DE-LUXE RECORD PLAYER KIT 

FOR ONLY £13.19.6 COMPLETE , m ^ 

An elegantly designed quality instrument that ' 

luilltls inl'i ;i siij>it1> rrjiroilui.-er. W t h I -.prrii . 

Garrard Auto Slfin unit and special Milliard hi«i 
quality o wall printed circuit valve amplifier, , 

vol. bass and treble controls. 8 x Sin. 10,000 line 
i Contemporary styled 2-tone cabinet, 
charcoal-grey and off-white with matching blue- 
reliel Sine l?l x 16 * 8in. A stylish 
unit ca|>able of quality reproduction. 
Circuit and construction details 2/6 
free with kit). 
COMPLETE KIT 0*0 «Q C 
' at , s nd inf. 12/6 L I J . I «J . O 
• 'ed 30 - extra, illuminated 
perspex control panel escutcheon, 
7/6 extra. Four con temporarv mount- 
in- legs, Sin. 10/6; !)in. 11 6; lL'iti 
12/6 extra, 




GARRARD UNITS AND PLINTHS 



LM.3000 Kecord Player with 
9 T.P. Stereo Cartridge. 
Limited number available. 8 gnS. 
Brand new as from factory. 



AT.60 De-luxe Auto-changer. . 

I2in. tnn.table. Super) ly 9* gnS. 

• tik. 01 ■ red* Less cartridge 



SP.25 De-luxe -ingle record 
player, lew cartridge. 
Parking and carr. on uny one 



9i gns. 



Garrard Plinth. The ideal 
modern mounting for the 
Canard Unit"* offered here. 
Will readily suit any hi-fi __ . 
set-up. Beaotifully mil-hed in #5/- 
Oak. Complete with contem- 
porary drop-on plastic cover. 
Packing anil carriage -t -. 

Garrard Cartridges. Hi-fi 
• jualitv turnover mono and 
stereo cartridge*. Mono Irom ot ., 
15/- Stereo from £OI- 

All post free. 

STYLUS REPLACEMENTS IS 

SAPPHIRES AND DIAMONDS AT 
VERY ATTRACTIVE PRICES. 



TRS KITS FOR MULLARD AMPLIFIERS 



MULLARD 3-3 

"3-3" Amp. ll-vulve Hi-Fi quality at 
reasonable irost. lias* Boost and Treble 

oaatrota, quality Motional ontpui tnm-- 

former. 40 e/s-25 kc/n ± LIB. 100 mV. for 
3W. les. than 1% distortion. Bronze 

I paneL Oamplate Kit only 

£7.10.0. (MR. 7/0. Wired and tested, 
£9.10.0. 



MULLARD 5-10 

5 valves LOW, 3 and 15 ohms output. 
Midlard's famous circuit with heavy 
duty ultra-linear qualitv output tfr. 
Basic amplifier kit price £9.19.6. Carr. 
7/8. Ready built 111 gns. 

Two Valve Pre-AmpVnit (Mullard Design) 
Kita £6.12.8. Built £8.10.0. Carriage 5/6. 



WE ARE SINCLAIR 
SPECIALIST SUPPLIERS 

lt> carry full llorki of thesr world-fnmou* 
nlt-firitirh driiau.i iurlndiuq Ihf Very latest 
ni luliiili'td hy tliit fainmu firm anil yi'iv 
prompt 'M/i.i/, 

Z.12 combined 12w. amp and pre-amp.. 
Imilt. 89/6; STEREO 25 de luxe ore-amo/ 
control unit (stereo) built £9.19.8: 
MICRO-6 six HiaKe veet-poekol reeehwr 
(kit). 69/6; MICRO-FM 7 traiisi-lor KM 
tuner-receiver (kit). £6.19.6. PZ.3 Mains 
;i ■ < ii'I'ly unit, £3.19.6. And the newest 
Sinclair desi'ens as released! 



7 VALVE AM/FM 
RG CHASSIS 

A ~uii.'ilily powerful, high performance 
inatraiiieDt for the keenest enthusiasts. 
l*rov|i!es tuniDg nn lung, medium an i i'.». 
w a v eba nds. :( ware-hand L/M.'FM. 
Pcnn--ahility tnning on F.S1. Large clear 
djal AA'.C, good neg. feedback. Magic eye. 
:i v. output. A.C. 200/360 v. Circuit 
diagrams available. Aligned, tested and 
ready for u«e £13.19.6. (Carr. and ins. 
7 fi.) 8.A.E. brings full details. 



TRANSISTOR COMPONENTS 



PEAK SOUND STEREO AMP 

With integrated pre-amp Uses Cir-Kil (or 
easv building. Model SA-8-8 ha« M mntelied 
transistois.; 20-20.000 c/aH : 3dB. Specially 
for use with high quality ceramic P.U.8. 
For S-8 ohm -peaker-. Ootpul 8.0 win i- pa 
channi'l. A high-i|iiallty lli-lnuncnl for easy 
bidlding and reliability. W0I III In saiulv 
under motor board to keep your oftblncrf work 
looking nllm. Oomplete with Inatruotionn 
£12.18.8. (p/p 4/-) 

PEAK SOUND POWER PACK— 76/- (p/p 5;«) 



UMgel IF. Trans. »/, »i. dla. 
W.yrad, etc. let, 2nd or 3rd IP 
6/6. One. Cnll" .'.-In. dla. Hod, and 
Long wave. 5/-. Ditto RBPANCO 
Jln. x Jln. x Jin. atamlnr.i type 
i-t,2nil and 3rd IF, One. Med and 
|onL'waveeu..6/-:l.>ouMi'Timr.L 
type ea., 6/9. Miniature Push- 
1'uii Driver Transf. (T>-pe TT4H) 
Ratio 0:1 . 6/-. Ditto O/P Tran.(. 
(To3ohni.-tvpeTT4H) HatloM:! 
6/-. Mltlgel in' Ohokes (for 

M. audi. W'.'oniH, Jiull. 7-Olull 
Klmll en., 2/6. 



POLYESTER Mini Condensers 
—Ideal (or P e.t OK. 2il"v. vg. 
•01 9d, -022 9d., -033 lid.. 0*7 
lid.. -Olif* 1/-. 1 1/1. 

MIDGET 
TRANSISTOR ELECTROLYTICS 
— TCC. elo. Std. range, a 1 values 
1 mfd— SO mfd. I2v,18v working 
eaeh 1/9. lOOmfd 12v, 2/-. 
1000 mfd liv 2/3. Speoial 
Eleotrolytics lor Transistor Mains 
Units. 1000 mfd. 2ov.. 3/9. 200(1 
mfd 60v, 6/6. 2000 mfd 75v, 7/6. 



PACKING AND 
CARRIAGE 

Up to i lb. 1/-; 
1 lb. 1/9d.; 3 lb. 
3/-; 5 lb. 3/9d.; 
8 lb. 4/6; except 
where otherwise 
stated. PAY- 

MENT. Cash with 
order or C.O.D. 



A GOOD WAY 
TO SPEND 



Send 3d. stamp to T.R.S. and you 
will receive our latest Bargain- 
packed lists by return. A great way 
to buy and save I 




TRS 



RADIO 



COMPONENT 
SPECIALISTS 

Established 1946 



70 BRIGSTOCK ROAD. THORNTON HEATH, SURREY 

Tel.: J HO 2188 Hours 9 a.m. — 6 p.m. 1 p.m. Wednesdays 



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CHOOSE THE RIGHT COURSE FROM 

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TELEVISION SERVICING, ELECTRONICS, 
COMPUTERS AND PROGRAMMING, 

ELECTRONIC TECHNICIANS, SERVOMECH- 
ANISMS, TELEMETRY, CLOSED CIRCUIT TV, 
INSTRUMENTATION, AND PRINCIPLES OF 
AUTOMATION. 

ALSO EXAMINATION COURSES FOR: 

Inst, of Electronic and Radio Engineers 
C. & G. Telecommunication Techns'. Cert. 
C. & G. Supplementary Studies 
R.T.E.B. Radio TV Servicing Cert. 
P.M.G. Certificates. Radio Amateurs' Exam. 

LEARN AS YOU BUILD 

Practical Radio Courses: Gain a sound knowledge of Radio 
as you build YOUR OWN 5-valve superhet Receiver and 
Transistor, Portable Signal Generator and High Quality 
Multitester. At the end of the course you have valuable 
practical equipment and a fund of personal knowledge and skill. 
ICS Practical Radio Courses open a new world to the keen 
amateur. 




ELECTRONIC ENGINEERING 



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ENGINEERING 



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EiFONOENCI 1CM00U 10H00M 




MEMBER OF THE ASSOCIATION 
OF BRITISH CORRESPONDENCE COLLEGES 



THERE IS AN 



ICS 



COURSE FOR YOU 




Whether you need a basic grounding, tuition to complete 
your technical qualifications, or further specialized 
knowledge, ICS can help you with a course individually 
adapted to your requirements. 

There is a place for you among the fully-trained men. 
They are the highly paid men — the men of the future. 
If you want to get to the top, or to succeed in your own 
business, put your technical training in our experienced 
hands. 

ICS Courses are written in clear, simple and direct language, 
fully illustrated and specially edited to facilitate individual 
home study. You will learn in the comfort of your own 
home — at your own speed. The unique ICS teac hing 
method embodies the teacher in the text; it combines 
expert practical experience with clearly explained theoretical 
training. Let ICS help you to develop your ambitions and 
ensure a successful future. Invest in your own capabilities. 

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and ICS technical courses in radio television and electronics 
PLUS details of over 150 specialised subjects. 



PLEASE SEND FREE BOOK ON. 
NAME 



ADDRESS 



OCCUPATION AGE 

INTERNATIONAL CORRESPONDENCE SCHOOLS 

Dept. 170, INTERTEXT HOUSE, PARKGATE ROAD, London, SW11 

2/67 



J 

721 



BRADFORD 10 North Pde. 

(Half-day Wed.) Tel. 25349 

BRISTOL 14 Lower Castle 
St. (Half-day Wed.) Tel. 22904 

BIRMINGHAM 30/31 Gt. 

Western Arcade, opp. Snow Hill 
Station. CENtral 1279. No half-day 

D E R B Y 26 Osmaston Rd . , 
The Spot (Half-day Wed.) Tel. 
41361 



DARLINGTON 13 Pos « 

House Wynd (Half-day Wednes- 
day) Tel.: 68043 

EDINBURGH m Lelm 

Street (Half-day Wed.) 

GLASGOW 328Argy.eS.. 
(No half-day) Tel.: CITy 4158 

HULL g, Paragon Street 
(Half-day Thursday) Tel.: 20505 




AUDIOTRINE PLINTHS 

for Record Playing 1 units. 
Teak finish cut for Garrard 
1000. 2000. 3000. AT6 Mk 2, 
AT60. SP25 or Goldring 
GL68. Available with clear 
CC/ Perspex cover as illustrated 
uo " £5.19.11. complete. 
ppo Consisting of Garrard SP25 fitted Goldring 
CS90 high compliance ceramic cartridge with 
diamond stylus, above plinth Only 1 Ql Rnc 

and cover. Normally £25. Carr. 15/- ,a 2 «>■»• 

Dpi As above but with Goldring Lenco GL68 Trans- 
cription unit and CS90 Cartridge. Normally 
oyer £33. Terms avail- Only og± fine 




able both units. 



Carr. 15/- 



AUDI0TRINE HIGH FIDELITY SPEAKERS 

Heavy cast construction. Latest high efficiency 
ceramic magnets. Dual Cone for exten- 
ded frequency range. Plastic treated 
surround giving low fundamental 
resonance. Response 35-20,000 c.p.s.. 
Impedance 3 or 15 ohms. Carr. 5/6. 
HF8UD 8 in. 10 WATT 4 Gns. 

IIF101D 10 in. 18 WATT 5 Gns. 

HF100D 10 in. 15 WATT £5-15.0 

IIF121D 12 in. 20 WATT £6.150 

HFI27P 12 in. 30 WAIT 9 t-ns. 

AUDIOTRINE HI-FI SPEAKER SYSTEMS 

Consisting of matched lam . 12,000 line. 
15 ohm high quality speaker: cross-over 
unit and Tweeter. Smooth response 
and extended frequency range ensure ,'Ttl 
surprisingly realistic reproduction. «H 
Standard 10 watt rating. Or C Rne 
Senior 20 watt inc. Fane ** uii». 
122/10 speaker 7 Gns. Carr. 7/6. Carr. 5/9 




MAIL ORDERS TO: 102 
Henconner Lane, Bram- 
ley, Leeds 13. No C.O.D. 
under £1. Terms C.W.O. 
or C.O.D. Postage 3/9 
extra under £2. 5/9 extra 
under £5. Trade supplied. 
S.A.E. with all enquiries 

please. HI-FI CATALOGUE NOW 

AVAILABLE price 3/3 post paid. 

Personal shoppers welcome. Open all day 

Sats. except High Holborn branch. 



LEICESTER 32 High Street 
(Half-day Thurs.) Tel.: 56420 

LEEDS 5.7 County (Mecca) 
Arcade (No half-day) Tel.: 28252 



LIVERPOOL 73 Dale st. 

(No half-day) Tel.: CENtral 3573 

L0 N D N 328 Edgware Road, 
W2 (Half-day Thurs.) Tel.: PAD 
1629. 96 High Holborn, WC1 
Tel.: HOL 9874 (Half-day Sat.) 



MANCHESTER Largewalk 

round store (No half-day) 60A- 
60B Oldham St. Tel.: CENtral 2778 

MIDDLESBROUGH 

106 Newport Road (Half-day 
Wednesday) Tel.: 47096 

NEWCASTLE upon tyne 

41 Blackett Street Opp Fenwicks 
Store (Half-day Wed.) Tel.: 21469 

SHEFFIELD 13 Exchange 
Street, Castle Market Bldgs. 
(Half-day Thursday) Tel.: 20716 



ALL LEADING MAKES OF HI-FI 
EQUIP. STOCKED Cash or Terms 



HI-FI LOUDSPEAKER ENCLOSURES 

All types of pleasing modern design 

acoustically lined 1 ported and in 

finishes or light Teak or medium Walnut. 
SE8. For optimum perform- 
ance with any HI-FI 81n. 
speaker. Size 22 x tn 17 Q 
15x7in. Carr. 7/6 M-v.li.9 

SE10. For lOln. Hi-Fi speaker 

with provision for tweeter. 

Size 24 x 15 x 8I11. re 10 n 

Oarr. 10/- tU«l».a 

SE12. For outstanding performance with 
any l21n. Hi-Fi speaker. Cut 
for tweeter. Size 24 x 20 x 8in. O Pno 
Or Deposit 27/- and 9 monthly ° Ullb. 
payments of 18/2 (Total £9.10.6.) Carr. 10/- 

FIIE8. Folded Horn type. Size]27 x 16 x lOin. 
Designed for high flux 81n. Q R ne 
speaker with which exception- ° uiij>. 
al quality can be obtained. Carr. 10/- 
Credit terms available. 




Tweeters R.A. 3 ohm or 1 5 ohm 25/9 




15 watt HI-FI TRANSISTORISED 

AMPLIFIER TYPE A15 

with integral pre- 
amp tone control 

stages. Output for 3, 
7.5 and 15 ohm spkrs. 
Kit includes Printed 
Circuit and aU parts including 9 Mullard 
or Newmarket latest re iq 11 Post 
type semi-conductors *-«*• i •»• I I 5;. 
Heat sink and full wiring instructions or 
with printed circuit fully wired and tested 
30/- extra. Frequency Response: — ldB 
20-20.000 c.p.s. Harmonic Distortion: 0.1 % 
measured at 1000 c.p.s. Hum and Noise: 
— 80dB. Sensitivity: 2mV. Bass Control: 
+ 9dB to — 14dB at 40 c.p.s. Treble Con- 
trol: + 8dB to — 13dB at 10 Kc/s. Suitable 
Power Pack K-r 39/6 or ready built 59/6. 
JASON VHF/FM TONER 
Complete kit with valve; 




HIGH FIDELITY LOUDSPEAKER UNITS 
Cabinets of latest styling Satin Teak or Walnut, 
acoustically lined (and ported where appro- 
priate. Credit Terras available on all units. 

MINI 8 8 WATT rating. 3 or 15 ohm. Frequency 
response 50-13,000 c.p.s. Specially des- 
igned high flux 5in. speaker with low 
fundamental resonance. Handsome 
Teak veneered cabinet. fR/1Q/11 
91 x 6b x 7in. Carr. 7/6 to / • *»/ • " 

I H t r fc 1 1 1 fc R ea iiy astounding per- 
formance. Size only 104 x 61 x 71in. 
Rating 10 watts. Frequency range 
45-20.000 c.p.s. Fitted specially designed 
Heavy cast 5in. speaker with large pole pieces, extra 
long voice coil and rubber cone surround. 11 fine 
Impedance 3 or 15 ohms. Carr. 7/6 ■ ■ **••»• 

The DORCHESTER SIze 24 x 15 x 8in. Fitted 

Audiotrine HF100D Speaker. Rating 15 watts. 
Impedance_15_ohms. Frequency _ 12GrlS 




Response 30-20,000 c.p.s. 



Carr. 15/- 



The GLOUCESTER Handsome -slim- Ipi 

line" cabinet. Size 24 x 20 x 8in. 12in. 1; .: 

High flux 12.000 line speaker. Cross-over R 

unit and Tweeter. Rating 10 watts. jspS-vR 
Smooth response 40-20.000 c.v. 

Impedance 15 ohms. 11 fine 8L ! ^^^i 

Carr. 15/- ' ' " ns - <|^ - - 

The BRONTE Size 22 x 15 x 7iin. Fitted Wharfe- 
dale Super 8 RSDD Speaker, with Roll surround 
and dual cone. Rating 6 watts. Impedance 11 fine 
15 ohms. Carr. 15/- le - ull!> - 



£6.19.11 



R.S.C. STEREO/TEN HIGH QUALITY AMPLIFIER 

A complete set of parts for the construction of a unit giving 5 watts high quality 
output on each channel (total 10 watts). Sensitivity is 50 millivolts. Suitable 
all crystal or ceramic stereo heads. Ganged Bass and Treble Controls. Provision 
is made for use as straight (monaural) 10 watt amplifier. Valve line-up ECC83. 
ECC83. EL84. EL84. EZ81. Outputs for 2-3 ohm speakers. Point to point wiring 
diagrams and Instructions supplied. Send S.A.E. for leaflet. 
Or supplied factory assembled with 12 months' guarantee for 11 gns. £ O ICQ 



Terms: Dep. 36/- and 9 monthly payments 25/5 (Total £13.4.9). 



Carr. 11/6 



R.S.C. STEREO 20 HIGH FIDELITY AMPLIFIER 

PROVIDING 10/14 WATT ULTRA UNBAR PISH-PIXL OUTPUT OX 
EACH CHANNEL. SUITABLE FOR •'MIKE". GRAM. RADIO OR TAPE. 
Employing valves ECC83, ECC83. ECL86. ECL86. ECL86. ECL86. EZ81. Frequency, 
Response: ±2dB 30-20,000 c.p.s. Ilum Level: 65dB down. Sensitivity: 5 millivolts 1 
maximum. Harmonic Distortion: (each channel): 0.2";,. •Four-position tone 
compensation and Input Selector Switch. •Stereo/Mono switch. 

•Will amplify direct from Tape Heads. -A- Neon panel indicator. •Handsome Perspex Frontplate. 
• Separate Bass "Lift" and "Cut" and treble "Lirt" and "Cut" controls. Output transformers are high- 
quality sectionally wound to required specification. Output matching for 3 and 15 ohm spkrs. on 1 A f» ne 
each channel. Complete set of parts, point-to-point wiring diagrams and instructions. Carr. 12/6 tH W" 
Or factory assembled, tested and supplied with our usual 12 months guarantee. 
Or Deposit £3 and 9 monthly payments 43/2 (Total £22.4.6). Send S.A.E. for leaflet. 




Carr. 12/6 



19 Gns. 



HS.C TFM1 TBANSISTOKISED VHF/FM KADI0 TUNER 



Total cost of parts 
with detailed wiring 
diagrams and instruc- 
tions. 1 OX Rn« 
Carr. 10/- xe ^^ "lib. 
Or factory built 
15! Gns. Or in Teak 
finished cabinet as 
illustrated 195 Gns. 
Terms: Deposit £5 and 9 

£22.U.O. 




mthly payments 89/- Total 



• High-sensitivity 

• 200-250V. A.C. Mains operation. • Sharp A.M. Rejection. • Drift- 
free reception. • Output ample for any amplifier (approx. 500 m.v.). 

• Simple alignment instructions. • Output available for feeding 
tuning meter. • Output for feeding Stereo Multi-plexer. • Tuner 
head using Silicon Planar Transistors. • Designed for standard 80 
ohm co-axial input. 

Made to visually match our Super 15 and 30 amplifiers and of the same high 
standard of performance and reliability. The pre-wired tuning head facili- 
tates speed and simplicity of construction. Printed circuitry. Only first 
grade transistors and components used. Our latest product giving you the 
best at half the cost of comparable units. 



Miniature 
Transistorised 
VHF/FM Tuner 

Battery operated. 
In plastic case 
complete with 
Telescopic Aerial 

£6.19.11 

Carr. 5/- 



R.S.C. SUP6R ISHiF/AMPUFm 



FULLY TRANSISTORISED 200/250v. A.C. Mains, 
OUTPUT 10 WATTS R.M.S. cont. into 15 ohms. 
15 WATTS R.M.S. cont. into 3-4 ohms. 
Maximum instantaneous Peak power output 28 watts. 
PRINTED CIRCUIT CONSTRUCTION. 
LATEST MULLARD TRANSISTORS. AD149, AD149, 
OC127Z, OC81Z, OC44. OC44, OC81Z, OC44, AC107. 
r. POSITION INPUT SELECTOR SWITCH 
EQUALISATION to Standard R.I.A.A. and C.C.I.R. 
Characteristics for Gram and Tape Heads. 
FULL TAPE MONITORING FACILITIES. 
SENSITIVITIES: Magnetic P.TJ. 4 mV. Crystal or 
Ceramic P.U. 400 mV. Microphone 4.5 mV. Tape Head 
2.5 mV. Radio/Aux or Ceramic P.U. 110 mV. 
FREQUENCY RESPONSE: - 2dB 20-20.000 C.p.s. 
TREBLE CONTROL: +15dB to— 14dB at 10 Kc/s. 

BASS CONTROL: +12dB to — 15dB at 50 c/s. HUM LEVEL: — 754B. 
HARMONIC DISTORTION at 10 Watts R.M.S. 1,000 c.p.s. 0.25%. 
NEGATIVE FEEDBACK: 52dB. 

Complete Kit of parts with f uU constructional details and 11 fi ns 

point to point wiring diagrams. Carr.Jl/- '■" 



TECHNICAL 
SPECIFICATIONS COMPARE MORE 
TnAN FAVOURABLY with SIMILAR 
AMPLIFIERS AT TWICE THE COST 



K,S.C.SUI>eRZQST£ReOAM/>UFm 




A DUAL CHANNEL VERSION OF THE SUPER 

15. Employing Twin Printed Circuits. Close tolerance 
Ganged Pots. Matched Components. 
CROSS TALK: — 52dB at 1.000 c.p.s. 
CONTROLS: 5 position Input Selector.Bass Control. 
Treble Control, Volume Control. Balance Control, Stereo/ 
Mono Switch, Tape Monitor Switch. Mains Switch. 
INPUT SOCKETS (Matched Pairs). (1) Magnetic P.U. 
(2) Ceramic or Crystal P.U. (3) Radio/Aux. (4) Tape Head/ 
Microphone. Operation of the Input Selector Switch 
assures appropriate equalisation. 

Rigid 18 s.w.g. Chassis. Size approx. 12in. Wide. 31n. High 
and 81n. Deep. Neon Panel Indicator. Attractive Facia 
Plate and Spun Silver Matching Knobs. Above facilities, etc., except for 
Ganging and Balance Control, apply also to Super 15. 

THESE UNITS ARE EMINENTLY SUITABLE FOR USE WITH 
ANY MAKE OF PICK-UP OR MICROPHONE (Crystal, Ceramic, 
Magnetic. Mining Coil. Ribbon) CURRENTLY AVAILABLE, 
SUPERB SOUND OUTPUT QUALITY CAN BE OBTAINED BY 
USING WITH FIRST RATE ANCILLARY EQUIPMENT. All 



point to point wiring diagrams. Carr.il/- ■■ *•■■«»• ■ usi^ior tviin rutst nait a-U'Illaki t*ii'ir.iit,u, axi 

Supplied factory built 15 Gns. Carr. 12/6. Terms: Deposit 49/- and 9 I required parts, point to point wiring diagrams and detailed 1oj_ n_„ 
monthly payments 33/9 (Total £17.12.9). Or fitted In beautiful Walnut or ■ Instructions. Carr. 13/9 ■"2 *"•"• 



Teak veneered cabinet as illustrated, 4 Gns. extra. 

ALL COMPONENTS ETC. ARE OF A HIGH STANDARD AND 

SUPPLIED BY LEADING BRITISH MANUFACTURERS. 



Unit factory built 25S Gns. or deposit 83/9 and 9 monthly payments 56/9 
(Total £29.14.6). Fitted cabinet as Super 15 291 Gns. Carr. 15/- or Deposit 
£4.14.9 and 9 mthly paymts 65/10 cTotal £34.7.3). Send S.A.E. for leaflet. 



722 




oaitlona for 

1<H Gns. 




AUDIOTRINE HI-FI TAPE RECORDER KIT 

REALISM AT INCREDIBLY LOW COST. S.A-E. for 

CAN BK ASSEMBLED IN AN HOCK. leaflet. 

ONLY 1 I'AIRS OF SOLDERED JOINTS PLUS MAINS. 

Incorporating the latest Magnavox Tapedeek. The Audiotrine 
High Qual I ty Tape. Amplifier with switched equalisation for each 
of 3 speeds. High Flux P.M. Speaker, empty Tape Spool, a Reel 
of Best Quali ty Tape and a handsome Portable Cabinet of latest 
styling finished dark grey leathercloth. Size 141 x 17 x 8Jin. and ■ 

circuit. Purchased separately would total approx. £34. Perform- \"* ' ■ ■■ ".» - 

ance equal to units in the E50-S60 class. Di-posii «■» f» 1 <% "El 

4 ens. and 9 mthly paymts 59/6 (Total 29) gn*.) /ho ut1S. \ 

4 Track Mndrl :ign>, extra. Carr. 19/6 ^«*^ '» - -~- 

L1NEAR TAPE I'RK-.V-MPI.IFIKR. Ijpe LP/1 Switched E<|iiaiisiit ion. I 
Recording at l.in..3iin.. Tjin. per sec, and Playback. K.MS4 lt>'cor<ling 
Level indicator. Designed primarily as the link between a Maenavox 
Tain- Deck and Hi-Fi amplifier suitable most Tape Docks. Terms available. 

R.S.C. 4/5 watt A5 HIGH GAIN AMPLIFIER 

A highly-sensitive 4-valvc quality amplifier for the home, small 
club. etc. Suitable for ail crystal or ceramic P.C. heads and practi- 
cally all "mikes". Separate Bass and Treble controls Riving "lift" 
and "cut". Hum level 71dB down. Negative Feedback ISdB. Reserve 
power supply 300v 25 ni.a., 6.3v 1.5 a. for Radio Tuner or Tape Pre- 
anip. lor A.C. mains 200-250v. Speaker output .1 ohms. Complete in every detail with 
fully punched enamelled chassis, point-to-point wiring diagrams and «« jm Q 
in-i met inns. Or assembled ready fur use 6 gns. plus 5/6 carr. BH I •" 

R.S.C. A10 30 WATT ULTRA LINEAR HI-FI AMPLIFIER 

Highly sensitive. Push-Pull high output, with Pre-amp./Tone Control 
Stages. Performance figures equal to most expensive amplifiers 
available. Hum level— 70dB. Frequency response i3dB 30-20,000 c/s. 
Specially designed sectionally wound ultra linear output transformer 
— J th 807 output valves. All first grade components. Valves EF86. 
EF86. ECC83. 807. 807, GZ34. Separate Bass and Treble Controls. 
Sensitivity 12 millivolts so that any kind of Microphone or 
Pick-up is suitable. Designed for Clubs, Schools. Theatres. 
Dance Halls or Outdoor Functions, etc. For use with Elec- 
Irronic Organ, Guitar. String Bass, etc. Gram, Radio or Tape. 
Reserve L.T. andH.T. for Radio Tuner. Two inputs with associat- 
ed volume controls so that two separate inputs such as Gram and "Mike" can be mixed 200- 
250v.50c/sA.C. mains. For 3 and 15 ohm speakers. Complete kit of parts in r* Me Can- 
fully punched chassis, point to point wiring diagrams and instructions. '« UIIo. v2/6 
Supplied factory built with EL34 output valves, 12 months guarantee for 15 tins. If required 
perforated cover with carrying handles can be supplied for 21/-. Send s.a.e. for leaflet. 
TKH MS: Deposit 48/- and 9 monthly payments of 33/7 (Total £17.10.3). 

R.S.C. A11 HIGH FIDELITY 12-14 WATT AMPLIFIER 

PUSH-PULL ULTRA LINEAR OUTPUT "BUILT-IN" 
TONE CONTROL PRE-AMP Two input sockets with asso- 
ciated controls allow mixing of "mike" and gram. etc.. etc. High 
sensitivity. ValvesECC83.ECC83.EL84.EL84.EZ81. High quality 
sectionally wound output transformer specially designed for 
Ultra Linear operation and reliable small condensers of current 
manufacture. INDIVIDUAL CONTROLS FOR BASS AND 
TREBLE. Frequency response ~3dB 30-20.000 c/s. Six negative 
feedback loops. Hum level — 60dB. SENSITIVITY 23 millivolts. 
Suitable for Crystal or Ceramic P.Us. all types "mikes". Com- 
parable with the very best designs. For Musical Instruments 
such as String Bass. Electronic Guitars, etc. Reserve Power provides 300v. 30mA and 
6.3v. 1.5a. for Radio Tuner or Tape Pre-amp. Size approx. 12 x 9 x 7in. For A.C. mains 200- 
250v. 50 c.p.s. Output for 3 and 15 ohm speakers. Kit complete to last nut. Chassis cq 1 C A 
lully punched. Full instructions and point-to-noint wiring diagrams (or factory ***• 1 0«U 
built £11.15.0). Metal cover with 2 handles available for 21/-. TERMS ON Carr 11/6 
ASSEMBLED UMTS: Deposit 36/6 and 9 monthly payments of 25/9 (Total £13.8.3). Send 
S.A.E. for illustrated leaflet :l Cabinets. Speakers. Mike's, etc. 





R.S.C. BASS-REGENT 50 WATT AMPLIFIER 

AN EXCEPTIONALLY POWERFUL HIGH QUALITY ALL-PURPOSE 
UNIT For lead, rhythm, bass guitar and all other musical instruments. 

_. UrrflUjjB » ^ or vocalists, gram, radio, tape and general public address 

L '•m™^^Egi m i!mm -A- UNUSUALLY POWERFUL^ LOUDSPEAKER COMBLNATION 



LONDON-NEWCASTLE 



New branches now 



14 Gns. 



R.S.C. COLUMN SPEAKERS Covered , n 

two-tone Rexine/Vynair. Ideal for vocalists 
and Public Address. 15 ohm matching. 
Type C5S. 15-20 watts. Fitted five 8in. high flux 
speakers. Overall si2e approx. 
42 x 10 x oin.Or Deposit 44 -and 
9mthlypmts31/5(Total £16.6.9) Carr. 10/- 
Typet'41'2. 40 watts. Fitted foul- 12in. 12.000 line 
10 watt speakers. Overall size n-t One 
56 x 14 x 9in. approx. Carr. 15/- *• ■ «'■». 
Or Deposit £3.11.0 and 9 monthly payments of 
46/7 (Total £34.10.3). 

30 WATT HI-FI AMPLIFIER 

for Guitar. Vocal or Instrumental Group 

A Four Input, two volume control Hi-Fi unit 
with separate Bass and 
Treble ' 'cut' " and ' 'boost' ' 
controls. Latest type 
valves. Housed in strong 
Rexine covered cabinet with twin 
carrying handles. Attractive black 
and gold perspex facia plate. 
For 200-250v. A.C. mains. Output for 
3 or 15 ohm speak- ■» "T r» n c c &n 
ers. Send S.A.E. for leaflet. Deposit ■ • wis. 12/6 
£3 and 9 monthly payments of 37/5 (Total £19.lfi.9>. 





12in. HIGH QUALITY LOUDSPEAKERS 

In walnut veneered cabinet. 10 Watt 
.Model. Gauss 12,000 lines. CA in 11 
Speech coil 3 or 15 ohms.*-* 1 ■•*•»' 

Carr. 7/6 
20 Watt Model. 15 ohm. Size f 7 1 Q 1 1 
18xl8xl0in. Gauss 12,000 lines. !■/ . I 3. 1 I 

Carr. 10/6 
.10 Watt Model. 15 ohms. 4(1 fi nc 
Gauss 17.000 lines. Carr. 12/6 lu "IIS. 
Credit Terms available on all above 
units. 




FANE HEAVY DUTY HI-FI SPEAKERS 

121n. 20 watt. Type 122/10. Post 7/6. 



5 Gns 



R.S.C. GRAM AMPLIFIER KIT. 3 watts output. 
Negative feedback. Controls: Vol.. Tone and Switch. 
Mains operation 200-250v. A.C. Fully isolated chassis. 
Circuit, etc. supplied. Only 44/9. Carr. 3/9. 



HIGH QUALITY 12in. 10 WATT SPEAKERS 

Flux Density 12.000 lines. 3 or 15 ohms. 



59/11 



L_J 



I?^ NS i S - T0R SALE Mullard OC71. OC72, ©C81, 2/11. 
OC44. OC4o. 3/11, OC75. 7/9, AF117. 6/9. Ediswan XA101 
XA112. XC101A. 3/9. Postage 6d. for up to 3 transistors. 



INTEREST 
CHARGES 
REFUNDED 

on H.P. and 
Credit Sale 
Accounts 
settled in 
3 months. 



consisting of a FANE HIGH FLUX 15in. 30 watt unit PLUS 

a FANE 12in. 20 watt unit with extended frequency response. •*• 4 Jack Inputs 

and two Volume Controls for simultaneous use of up to 4 pick-ups or "mikes". 

ir Cabinets covered in two-tone Rexine/Vynair with gold trimming. Fitted carry- 
ing handles. * Separate Bass and Treble Controls giving "lift" and "cut". 

AQ± (Jnc send S.A.E. for leaflet. Or call at one of our many branches and 

„ 2 *?"' , ■ compare the Bass-Regent with units at three times the cost. 

Carr. 30/- Or deposit £7.17.6 and 9 monthly payments of £5.10.10. (Total 55 gns.» 



R.S.C. MAINS TRANSFORMERS 



B20 MULTI-PURPOSE AMPLIFIER 
especially suitable for Bass Guitar 

Incorporating massive 15in. high flux loud- 
speaker. Rating 25 watts. Individual bass and 
treble controls. Two jack inputs separately 
controlled. Substantial cabinet attractively 
finished in Rexine and Vynair. Size approx. 
24 x 21 x llln. Send S.A.E. for leaflet 
Or Deposit £4.14.6 and 9 monthly 
payments of 66/- (Total £34.8.6). Carr. 17/6 



G15 15 WATT AMPLIFIER for Lead or 
»— - 1 Rhythm Guitar, Mike, Gram or Radio 

I 1 I ili-h-fldcllty output. Separate bass and treble 

1 I controls. Twin separately controlled inputs so 

I that two Instruments or "mike" and pick-ups 



29| Gns. 



can be used at the same time. Heavy Duty 12in. 

20 watt Speaker. Cabinet covered in attractive 

Rexine/Vynair. Size 18 x 18 x 8in. Deposit 3 gns. 

1Q— Gns CaiT - and 9 monthly payments of 43/7 
1 j 2 una. 15/ ._ (Total £.jo.i 5 . :l) . s.A.E. for leaflet. 



LINEAR TREMOLO PRE-AMP UNIT Sultab j ef0 r 
use with any of our Amplifiers. Controls are Speed 
(frequency of interruptions). Depth (for A I f*' n c 
heavy or light effect). Volume and Switch. *5 *"'»• 

POWER PACK KIT Conslsting of Mains ^ 

former. Metal Rectifier. Electrolytics, smoothing 
choke, chassis and circuit. 200/250v. A.C. 00 11 
mains. Output 250v. 60mA, 6.3v. 2a Supplied *»•' ■ • 
with case in lieu of chassis 26/11. Or assembled 39/11. 

R.S.C. BATTERY/ MAINS CONVERSION UNITS 

Type BM1. An all-dry battery 
eliminator. Size 5$ x 41 x 2in. approx. 
Completely replaces batteries sup- 
plying 1.5v. and 90v. where A.C. 
mains 200/250v. 50 c/s is available. 
Complete kit with diagram 49/9 or 
ready for use 59/11. 

SELENIUM RECTIFIERS F.W. (Bridged) 

All 6/12 v. D.C. output. Max A.C. Input 18 v. 

1 a. 3/11. 2 a. 6/11. 3 a. 9/9. 4 a. 12/9. 6 a. 15/9. 




G20 SUPER TWIN AMPLIFIER 

Rating 20 watts (max.) lor vocalists. Lead or Rhythm Guitar 
n separately controlled Input?. Two 12in. High Flux 



Speakers (Total rating 30 watts). Attract 
covered cabinet. Terms: Deposit £4.6.8 and 
9 monthly payment* 50/- (Total £26.16.8i. 



23 



;/Vy 
Carr. 17/6 

Gns. 



SPECIAL PURCHASE! 12in. 30 WATT HEAVY 
DUTY 15 ohm LOUDSPEAKERS 7 ^j. 12 ' 6 

Flux Density 17.000 lines. Folly Guaranteed. ' GNS. 
Outstanding value at normal price of approx. £12. Oi deposit 
83/10 and monthly payments of 16/6 (Total £8.3.4). 



HEAVY DUTYSELENIUM RECTIFIERS 



12v. 15 amps. F.W. (Bridged). 



Only 



19'9 



HEAVY DUTY BATTERY CHARGER KITS 6/12 v. 

Consisting of Mains Trans. 200-250 v.. Rectifier. 
Ammeter. Variable Charge Rate Selector. Panels. 
Plugs. Fuses and Holders. Fully punched stove 

aWc e u!t case 4a 49/11 6a 69/11 



14/11 
15/11 



19/9 
33/9 
33/9 

41/9 



67/9 
69/9 
79/9 



19/9 
21/9 



32/9 
32/9 



FULLY GUARANTEED. Interleaved snd Impreg- 
nated. Primaries 200-250v. 50 c/s. Screened. 
MIDGET CLAMPED TYPE 2i x 8 i x 21in. 

250v., 60mA. 6.3v. '2a 

230-0-250V., 60mA, 6.3v. 2a 

FOLLY SHROUDED UPRIGHT MOUNTING 
250-0-250V. 60mA, 6.3v. 2a. 0-5-6.3v. 2a, 

2$ x 3 x Sin 

250-0-250v. 100mA, 6.3v. 4a, 0-5-6.3v. 3a. . . 
300-0-300V. 100mA, 6.3v. 4a, 0-5-6.3V. 3a. . . 
300-0-300V. 130mA, 6.3v. 4a c.t„ 6.3v. la. 

For Mullard .110 Amplifier 

350-0-350v. 100mA, 6.3v. 4a, 0-5-6.3v. 3a. . . 
330-0-350v. 150mA, fi.3v. 4a, 0-5-6.3V. 3a. . . 

425-0-425V. 200mA. 6.3v. 4a, c.t„ 5v. 3» 

425-0-423V. 200mA, 6.3v. 4a, S.3v. 4a, 5v. 3a 
430-0-450V. 250mA, 6.3v. 4a, c.t„ 5v. 3a . . 
TOP SHROUDED DROP-THROUGH TYPE 

230-0-250V. 70mA. 6'.3v. 2a.. 0-5-0.3V. 2a 

250-0-250V. 100mA, 6.3v. 3.5a 

250-0-250V. 100mA, 6.3v. 2a, 0.3v. la 

850-0-350V. 80mA, 0.3v. 2a, 0-5-fl.3v. 2a . , . . 
250-0-250V. lOOinA, G.3v. 4a, 0-5-H.3V. 3a . , 
300-0-300v. 100mA, (i.3v. 4a, 0-5-0.3v. 3a . . 
300-0-300v. 130mA, 6.3v. 4a, 0-5-li.3v. la. 

Suitable for Mullard 51 Amplifier 39/9 

350-0-350 v. 100mA, 0.3v. 4a, 0-S-6.3V. 3a .. 32/9 

350-0-350V. 150mA, 6.3v. 4a, 0-5-C.3v. 3a . . 39/11 

FILAMENT or TRANSISTOR POWER PACK Types 

6.3v. 1.5a 6/9, «.3v. 2a 7/9, Mr, 3a 8/9, 0.3v. 6» 19/9. 

12v. la 8/9. 12v. 3a or 24v. 1.5a 19/9, 0-9-lSv. Its, 

15/9. 0-25-35-42v. 2a 27/9. 

CHARGER TRANSFORMERS 0-9-15v. Ija, 13/9, 

0-9-15v.24a,16/9.n-S-15v. 3a, 18/9.0-9-15v.Sa,21/9, 

0-9-lov. 6a. 25/11, 0-9- 15v. Sa, 31/9. 

AUTO (Step UP/Step DOWN) TRANSFORMERS 

0-110/120v.-200-230-250v. 

50-80 watts 14/9 250 watte .. 

130 watts 29/11 500 watte .. 

OUTPUT TRANSFORMERS 

Standard Pentode 5,0000 to 3D or 7,0000 

to 3D 

Push-Pull S watts EL84 to 3D or 150 

Push-pull 10-12 watu 0V6 to 3 O or 15 Q 
Push-pull 10-12 watts to match 0V6 to 3, 6, 8 

or 150 

Push-pull EL84 to 3 or 15 Q 10-12 watts 

Push-pull Ultra Linear for Mullard 510, etc 
Push-pull 15-18 watts, sectionally wound 6L8, 

KT66, etc., for 3 or 15Q 

Push-pull 20 watt high quality sectionally 

wound, EL34, 6L6, KT66, etc.. to 3 or 

ISO fully shrouded 6S/9 

SMOOTHING CHOKES 
150 mA. 7-10H, 250 fi 12/9. 
100 mA, 10H, 200 3/11. 
80 mA, 10H, 3500 7/9. 
60 mA, 10H, 400 O 4/11. 



49/9 
99/9 



7/9 
11/9 
19/9 

21/9 
19/9 
35/9 

22/9 



[ HI-FI CEKTRES LTD. J 



723 



Why freeze 
this Winter 

and next — and next 




When in 2 days 
and at a cost of 
only £195 you 
can have COM- 
PLETE central 
heating by free- 
flow warm air? 



Compact and reliable, the EFEL with its 
powerful output of 42,000 B.T.U's boosts a 
free-flow of warm air throughout your home. 
Burning 24 hours a day and providing down- 
stairs temperatures from 70° to 75° and upstairs 
from 60° to 65°, the EFEL running costs are 
only 15/- a week. 

COMPLETELY INSTALLED IN 2 DAYS FOR £195 




OIL-FIRED CENTRAL HEATING 



AVAILABLE ON THE REGENT 
PERSONAL LOAN SCHEME- 
NO DEPOSIT AND UP TO 
5 YEARS TO PAY 




To: HOUSEHOLD HEATING SUPPLIES LTD. 
7 Ilford Lane. Ilford. Essex (ILF 5898). 
Please send me further details. 

Name 

Address 

Tel P-W. 



CALLING ALL 

SKILLED 
TECHNICIANS! 

If you're aged 23-30, this 

could be just the opportunity 

you're looking for. 

The Army needs men trained in the following skills, 
and who have the appropriate Ordinary National 
Certificate or City & Guilds qualifications. 

ELECTRONIC TECHNICIANS AIRCRAFT TECHNICIANS 
MOTOR MECHANIC/AUTOMOBILE ENGINEER 

PROMOTION TO SERGEANT SIX WEEKS AFTER YOU JOIN! 

Here's your chance to train as one of the Army's top 
class technicians — an Artificer in the Royal Electrical 
and Mechanical Engineers — specializing in vehicles, 
aircraft, electronics or radio. 

Today's Army is equipped with all the most mod- 
ern technical equipment — radio transmitters, closed 
circuit TV, gunfire control equipment, radio trans- 
ceivers, helicopters. That's the kind of exciting equip- 
ment you could be working on as a R.E.M.E. Artificer. 

EARN £987 A YEAR AND MORE! 

This year every soldier in the Army is better off. As a 
sergeant, you will earn £987 a year — and all your food 
and lodging are free. Married men get an additional 
£236. Staff Sergeants earn more and you'll be given 
every chance to work for still further promotion and 
still better pay. 

WANT TO KNOW MORE? 
SEND OFF THE COUPON TODAY! 



TO : ARMY CAREERS MP6(a) 5 LANSDOWNE HOUSE, LONDON W. I 

Please send me full details of how to become an Artificer 

NAME - _ 



ADDRESS 
TOWN 

COUNTY 

M221502 



DATE OF BIRTH 



( You must be resident in the UK) 



724 




EEK.2S-2& Project 
Constructional Kit 




you. 



* *> 



S A. SONS watt 
Integrated Stereo Amplifier 





the 



complete ran 





TEAS&-R.F. Signal 
Generator 




EAGLE 




r 



When the "Eagle" Brand was launched 10 years ago it was 
impossible to foresee that in such a short time the range would 
grow to cover over 500 items, all carrying the "Eagle" name. 
Whether you are interested in Hi-Fi, Amateur Radio, Do-it- 
Yourself projects or any field of Electronics, "Eagle" offer you 
the widest choice of sensibly priced products and by the end of 
the year we plan to increase our range to cover the formidable 
total of 700 items. 

If you would like to study our entire range in the leisure of your 
home we will be delighted to send you our catalogue free of 
charge or why not ask your local dealer (there are over 6,000 
"Eagle" stockists) to show you the latest "Eagle" Products today ! 



To: EAGLE PRODUCTS, Dept. PW.2, 
Coptic Street, London, W.C.I. 

Please send me catalogue of the entire "Eagle' 
range. 

Name 



n 



Address 



725 



HI-FI AMPLIFIERS 



TUNERS 



RECORD PLAYERS 




TRANSISTOR MIXER. MODEL TM-1. A must for the tape 
enthusiast. Four channels. Battery operated. Similar styling to 
Model AA-22U Amplifier. Kit £11.16.6. Assembled £16.17.6 

20+20W TRANSISTOR STEREO AMPLIFIER. Model AA- 
22U. Outstanding performance and appearance. 5 stereo inputs 
each channel. 20 transistor. 10 diode circuit. Kit £39.10.0 
Assembled £57.10.0 (Cabinet £2.5.0 extra). 

GARRARD AUTO/RECORD PLAYER. Model AT-60. less 
cartridge £13.1.7 With Decca Deram pick-up £17.16.1 incl. P.T. 

Many other Garrard models available, ask for Lists. 

HI-FI MONO AMPLIFIER. Model MA-5. A general purpose 
5W Amplifier, with inputs for Gram., Radio. Modern functional 
appearance. Kit £11.9.6 Assembled £15.15.0 



10W 

POWER 

AMP. 

MA-12 




9 + 9W 
STEREO 
AMP. 
S-99 



".' 




HI-FI MONO AMPLIFIER. Model MA-12. 10W output, wide freq. 
range, low distortion. Use with control units. Models UMC-1 (Mono) 
or USC-1 (Stereo). Kit£12.18.0 Assembled £16.18.0 

3+3W STEREO AMPLIFIER. Model S-33. An easy-to-build. low 
cost unit. 2 inputs per channel. Kit £13.7.6 Assembled £18.18.0 

DE LUXE STEREO AMPLIFIER. Model S-33H. De luxe version of 
the S-33 with two-tone grey perspex panel, and high sensitivity neces- 
sary to accept the Decca Deram pick-up. Kit £15.17.6 Assembled £21.7.6 

HI-FI STEREO AMPLIFIER. Model S-99. 9 + 9W output. Ganged 
controls. Stereo/Mono gram, radio and tape inputs. Push-button selec- 
tion. Printed circuit construction. Kit £28.9.6 Assembled £38.9.6 

POWER SUPPLY UNIT. Model MGP-1. Input 100/1 20V. 200/250V. 
40-60 c/s. Output 6-3V, 2-5A A.C. 200, 250. 270V, 120mA max. D.C. 

Kit £5.12.6 Assembled £7.2.6 



Hc.a±h-kJ±. 



Make the most of your leisure time. 



m^ttmifmM 



New ! 




HIGH PERFORMANCE CAR RADIO, CR-1. Superb LW/MW 
entertainment, wherever you drive. For 12v. pos or neg. earth 
systems. Tastefully styled to match any car colour scheme. Many 
special features. Send for details. Kit (less speaker) £12.17.0., 
L/S.6" x 4" £1.4.5 extra. Prices incl. P.T. 



RADIOS 




"OXFORD" LUXURY PORTABLE 
Model UXR-2. Specially designed for 
use as a domestic or personal portable 
receiver. Many features, including solid 
leather case. Kit £14.18.0 incl. P.T. 

TRANSISTOR PORTABLE. Model 

UXR-1. Pre-aligned I.F. transformers, 
printed circuit. Covers L.W. and M.W. 
Has 7" x 4" loudspeaker. Real hide case. 
Kit £12.11.0 incl. P.T. 

JUNIOR EXPERIMENTAL WORKSHOP 
Model EW-1. More than a toy I Will 
make over 20 exciting electronic devices, 
incl.: Radios, Burglar Alarms, etc. 72 
page Manual. The ideal present! 

Kit £7.13.6 incl. P.T. 

TRANSISTOR STEREO FM TUNER. Elegantly designed to 
match the Stereo Amplifier, model AA-22U see above. Many 
special features include built-in power supply. Available in two 
units sold separately, can be built for a case built for 6. 

TOTAL PRICE KIT (STEREO) £24.18.0 incl. P.T. Cabinet £2.5.0 
extra. (MONO) version £20.19.0 Kit. 



UXR-1 



»♦♦♦♦♦♦♦■ 



WELCOME TO OUR LONDON HEATHKIT CENTRE 

233 Tottenham Court Road, W.1 

We open MONDAY-SATURDAY 9 a.m.-5.30 p.m. 

THURSDAY .. . . 1 1 a.m.-2.30 p.m. 

Telephone No: MUSEUM 7349 

WHEN YOU ARE IN TOWN. WE HOPE YOU WILL VISIT US THERE 




TEST INSTRUMENTS 

Our wide range includes: 
3' LOW-PRICED SERVICE OSCILLO- 
SCOPE. Model OS-2. Compact size 5" x 
7j}" x 12" deep. Wt. only 9|lb. "Y" bandwidth 
2 c/s-3 Mc/s ±3dB Sensitivity 100mV/cm. 
T/B 20 c/s-200 kc/s in four ranges, fitted mu- 
metal CRT Shield. Modern functional styling. 
Kit £23.18.0 Assembled £31.18.0 

5' GEN. -PURPOSE OSCILLOSCOPE. 
Model 10-12U. An outstanding model with 
professional specification and styling. "Y" 
band width 3c/s-4-5 Mc/s =3dB. T/B 10 c/s- 
500 kc/s. Kit £35.17.6. Assembled £45.15.0 

DE LUXE LARGE-SCALE VALVE VOLT- 
METER. Model IM-13U. Circuit and speci- 
fication based on the well-known model V-7A M 
but with many worth-while refinements. 6" ll 
Ernest Turner meter. Unique gimbal bracket If 
allows operation of instrument in many posi- ill 
tions. Modern styling. 

Kit £18.18.0 Assembled £26.18.0 VVM, 1M-13U 



AUDIO SIGNAL GENERATOR. Model AG-9U. 

10 c/s to 100 kc/s, switch selected. Distortion less than 
0-1%, 10V sine wave output metered in volts and dB's. 

Kit £23.15.0 Assembled £31.15.0 
VALVE VOLTMETER. Model V-7A. 7 voltage 
ranges d.c, volts to 1,500 A.C. to 1,500 r.m.s. and 4,000 
peak to peak. Resistance 0-1 £1 to 1.000MH with internal 
battery. D.C. input resistance 11MD. dB measure- 
ment, has centre-zero scale. Complete with test prods 
leads and standardising battery. 

Kit £13.18.6 Assembled £19.18.6 

MULTIMETER. Model MM-1U. Ranges 0-1 5V to 
1 ,500V a.c. and d.c ; 150izA to 15A d.c; 0-2H to 20M<> 
4 J" 50u-A meter. Kit £12.18.0 Assembled £18.11.6 

R.F. SIGNAL GENERATOR. Model RF- 
1U. Up to 100 Mc/s fundamental and 200 
Mc/s on harmonics. Up to 100mV output. 
Kit £13.1 8.0 Assembled £20.8.0 
SINE/SQUARE GENERATOR. Model 
1G-82U. Freq. range 20 c/s-1 Mc/s in 5 
bands less than 0-5% sine wave dist. less 
than 0*1 5u. sec. sq. wave rise time. 

Kit £25.1 5.0 Assembled £37.1 5.0 




RF-1U 




IG-82U 



TRANSISTOR POWER SUPPLY. 

Model IP-20U. Up to 50V, 1-5A output. 

Ideal for Laboratory use. Compact size. 

Kit £35.8.0 Assembled £47.8.0 



Prices and specifica- 
tions subject to change 
without notice 



726 



TAPE AMPLIFIERS 



TAPE DECKS 



CONTROL UNITS 




FM 
TUNER 
FM-4U 




STUDIO- 

MATIC 

DECK 



HI-FI FM TUNER. Model FM-4U. Available in two units. R.F. 
tuning unit (£2.15.0 incl. P.T.) with I.F. output of 10-7 Mc/s 
and I.F. amplifier unit, with power supply and valves (£13.13.0). 
For free standing or cabinet mounting. Total Kit £16.8.0 

(Multiplex adaptor available, as extra). 

HI-FI AM/FM TUNER. Model AFM-1. Available in two units 
which, for your convenience, are sold separately. Tuning heart 
(AFM-T1— £4.13.6 incl. P.T.) and I.F. amplifier (AFM-A1 — 
£22.11.6). Printed circuit board. 8 valves. Covers L.W., M.W., 
S.W., and F.M. Built-in power supply. Total Kit £27.5.0 

(Multiplex adaptor available, as extra). 

STUDIOMATIC "363" TAPE DECK. The finest buy in its 
price range. Operating speed: 1|", 3|" and 7i" p.s. Two tracks, 
"wow" and "flutter" not greater than 0-15% at 7J" p.s. £13.10.0 
With TA-1 M Tape Pre-amplifier kit £31 .5.6 




TRUVOX 
DECK 




AM/FM 
TUNER 



TRUVOX D-93 TAPE DECKS. High quality stereo/mono tape decks. 
D93/2, i track, £36.1 5.0 D93/4, J track, £36.1 5.0 

TAPE RECORDING/PLAYBACK AMPLIFIER. 

Mono Model TA-1 M Kit £19.18.0 Assembled £28.18.0 

Stereo Model TA-1 S Kit £25.10.0 Assembled £35.18.0 

HI-FI CABINETS. A wide range available for example: — 
Malvern Kit £18.1.0 incl. P.T. 

MONO CONTROL UNIT. Model UMC-1. Designed to work with 
the MA-12 or similar amplifier requiring 0-25V or less for full output 
5 inputs. Baxandall type controls. Kit £9.2.6 Assembled £14.2.6 

STEREO CONTROL UNIT. Model USC-1. Push-button selection 
accurately matched ganged controls to ±1dB. Rumble and variable low 
pass filters. Printed circuit boards. Kit £19.19.0 Assembled £27.5.0 



Enjoy building a Heath kit model 




MULTIPLEX 
DECODER SD-1 

For receiving Stereo FM. 

Convert your existing FM 

Mono receiver to stereo with 

this low cost, self powered 

unit. Fully transistorised. 

Kit £8.1 0.0 Assembled £1 2.5.0 

Styled to match British Heathkit models. 




SPEAKER SYSTEMS 




Berkeley 



HI-FI SPEAKER SYSTEM. Model 

SSU-1. Ducted-port bass reflex cabinet 
"in the white". Two speakers. Vertical 
horizontal models with legs. Kit £12.12.0, 
without legs, Kit £11.17.6 incl. P.T. 

The BERKELEY SLIM-LINE 

SPEAKER SYSTEM, fully finished 
walnut veneered cabinet for faster con- 
struction. Special 12" bass unit and 
4" mid/high frequency unit. Range 
30-1 7,000 c/s. Size 26" x 1 7" only 7£" deep. 
Modern attractive styling. Excellent value. 
Kit £1 9.1 0.0 Assembled £24.0.0 

COTSWOLD SPEAKER SYSTEMS. 

Outstanding performance for price. 
MPS: Size 36° x 16 J" x 14" deep. 

Kit £25.12.0 Assembled £33.17.0 
STANDARD: Size 26" x 23" x 14J" deep. 

Kit £25.12.0 Assembled £33.17.0 




Deferred terms available in UK over £10 
Prices quoted are Mail Order prices 



DAYSTR0M LTD 



Dept. P.W. — 2 
GLOUCESTER 



'AMATEUR" EQUIPMENT 



80-10m TRANSMITTER, DX-40U. 

Power inputs 75W. C.W., 60W peak 
CC phone. Output 40W to aerial. 
Provision for VFO. 

Kit £29.1 9.0 Assembled £41 .8.0 

AMATEUR BANDS RECEIVER 
Model RA-1. To cover all the Amateur 
Bands from 160-10 metres. Many special 
features, including: half-lattice crystal 
filter; 8 valves; signal strength "S" 
meter; tuned R.F. Amp. stage. 

Kit £39.6.6 Assembled £52.10.0 

160-10M TRANSMITTER. Model DX- 
100U. Careful design has achieved high 
performance and stability. Completely 
self-contained. 

Kit £81 .1 0.0 Assembled £1 06.1 5.0 

COMMUNICATIONS TYPE RECEIVER. Model 
RG-1. A high performance, low cost receiver for the 
discriminating listener. Frequency coverage: 600 
kc/s-1-5 Mc/s and 1-7 Mc/s-32 Mc/s. 

Kit £39.16.0 Assembled £53.0.0 

REFLECTED POWER METER and SWR 
BRIDGE. Model HM-11U. Indicates reliably but 
inexpensively, whether the RF power output of your 
TX is being transferred efficiently to radiating 
antenna. Kit £8.10.0 Assembled £10.15.0 




DX-40U 



l||ill | il 




RA-1 




HM-11U 



OUTSTANDING "AMATEUR" EQUIPMENT 
A wide range of American Amateur SSB equip- 
ment is now available in the U.K. Why not send 
for full details of range, for example: 

FILTER TYPE SSB TRANSCEIVERS 

Models for 80. 40 or 20 metre bands. 
Model HW-12 (80M) £67.10.0 Kit 
Model HW-22 (40M)-i £66.0.0 each Kit. 
Model HW-32 (20M) / price inc. duty, etc. 




80M Transceiver 
HW-12 



Without obligation please send me (Tick here)"! 

FREE BRITISH HEATHKIT CATALOGUE □ 

FULL DETAILS OF MODEL(S) 

(.Please write in BLOCK CAPITALS) 
NAME 



ADDRESS. 



DEPT. P.W.2 



727 



LaskTs 

RADIO 



FOR THE FINEST VALUE AND 
TO HOME CONSTRUCTORS 



TRANSISTOR PORTABLES 



II' ro;i"-'.i >,i,t Construction Parcel* to be Ike finest value available on the home ron- 
ttturiit.n ui'frk-t. If on r-'cript you feel not competent to build the set. you may return it 
01 t-.< ,11 ,l ti'ii/iiu 7 days, when the sum paid trill be refunded lean postage. 




ir LONG WAVEBAND 
COVERAGE IS NOW AVAIL- 
ABLE FOR THE SKYROVER 

A simple additional circuit provides 
coverage of the 1100/1950M. baud (in- 
cluding 1500M. Light programme). This 
b in addition to all existing Medium 
and Short wavebands. All necessary 
component' 1 with construction data. 

Only 10/- extra Post Free. 
This conversion Is suitable for receivers 
that have already been constructed. 
Data 2/6 extra: Kefnnded If yon pnrcha 
All component* available separatelv. 



THE SKYROVER De Luxe 

7 transistor plus 2 diode superhet, 6 wave- 
band portable receiver covering the full 
Medium Waveband and Short Waveband 
31-94M and also 4 separate switched band- 
spread ranges, 13M., IBM.. ISM., and 2BM.. 
with Band Spread Tuning for accurate 
Station Selection. The coil pack and tuning 
heart- is completely factory assembled, 
wired and tested. The remaining MS- 
can be completed in under three hours from 
our easy to follow, stage by stage in-.iriu- 
tions. Superhet, 470 Kc/s. All Mallard 
Transistors and Diode. Uses 4 U2 batteries. 
Oin. Ceramic Magnet P.M. Speaker. Easy to 
read Dial Scale, 500 M\V Output. Telescopic 
Aerial and Pcrritc Rod Aerial. Tone 
Circuit Is incorporated, with separate Tone 
Control in addition to Volume Control. 
Tuning Control and Waveband Selector, 
In a wood cabinet, size 11 J x HJ x 3in. 
covered with a washable material, with 
plastic trim and carrying handle. Car 
aerial socket fitted. 



H.P. Terms: 60/- deposit and 11 monthly 
payments of 12/9. Total H.P.P. £10.0.8 

I the parcel. Four TJ2 batteries 3/4 extra. 




TAPE RECORDERS 



MAGNAVOX 363 

TAPE DECKS ^~ 

The very latest S speed model — 12, 3}. 7} J J BWBB WI 

rps. available with either ! track or J USHi^^^^mil TrHtfRi 

.■•ad. Features Include: pause con- ■■ - 

trol; digital countei; fast forward and re- 
wind; new 4 pole fully screened induction 
motor. Interlocking keys. Size of top plate 
l:u x llin. x .ijln. deep below unit plate. j ^3^«HI 
For 200'2f»0v. A.C. mains, 50 cps operation. 
N •■-.», uivi-ed and fully guaranteed. 

Lasky's Price ^f £10.10.0 
Lasky's Price *£$* £1 3.9.6 

Carriage and Packing 7H extra. 

NEW MARTIN TAPE RECORD/REPLAY AMPS. 

Now available from stock — for use with the Magnavox 383 Tape Deck. 

i track model LASKY'S PRICE £14.19.6 Carrlageand 

i track model LASKY'S PRICE £15.19.6 Packing 4'fl extra. 

Optional extra: Control panel escutcheon to take deck and amplifier oo&tl >'- 
LASKY'S PRICE 12/6 Posl A- Packing 2,6. 

INTERNATIONAL TAPE Famous American Brand— Fully Guaranteed 

MB. Message tape, lSOft 2 6 BSin. Long play, 1200 ft. Acetate 18 6 

.lin. Message taiu\ 225ft 8 9 5"in. Standard play, 8»0fl. PVC 118 

Sin. Message tape, 300ft 76 6-Jin. Long play. 1200ft. Mylar .. 15 

8}ln. Triple plav, 000ft. Mylar 10 SJin. Triple play. 2400ft. Mylar 45 

4ln. Triple plav. 900ft. Mvlar 17 6 7in. Standard play, 1900ft. Acet.lB 6 

Sin. Double plav, 1200ft. Mylar 15 7in. Standard play, 1200ft. Mylarl2 6 

r.in. Long play, SOOft. Acetate 10 7in. Long play. 1800ft. Mylar 19 6 

Bin. Standard plav, 600ft. PVO 8 6 7in. Double play. 2400ft. Mylar 2B 

RS. Triple plav, 1800ft. Mvlar 85 "in. Long play, ISOOft. Acetate 15 

BJIn. Double play. 1800ft. Mylar 22 6 7in. Triple play, 3600ft. Mylar 50 

P. & P. 1/- extra per reel. 4 reels and over Post Free 
Full range of Philips prerecorded cassettes — send S.A.E. for list. 



MICROPHONES 



THE VERY LATEST MARVELS OF 
ELEC TR ONIC MINI A TURISA TION 

THE TTC MODEL B4002 FM WIRELESS 
MICROPHONES 

Highly sensitive — suitable for either static or mobile use. Signals 
can be picked up by any FM radio or tuner which receives fraq 

96— 1 "4 He - over several hundred yards. Size only 8x9) 
x lln. fin leather case). Operates in one PP3 type battery. ('■■■ 
with neck cord, clip o n dynamic extension mike (4 x J x s /i«m.:i and 
battery. LASKY'S PRICE 10 Gns. Post Free anywhere in world. 
THE TTC MODEL 13:500. More powerful version of above — siae 71 
on one PP3 type battery. LASKY'S PRICE 12 Gns. Post Freeanywh 





CONSTRUCTORS BARGAINS 



SPECIAL PURCHASE— UHF/VHFTV TUNERS 

Well known British makers surplus stocks. Sow available for the first 
time to the Home Constructor. Add 2/6 Post and Packing on each. 

TRANSISTORISED UHF MINIATURE MODEL 1 

Shielded metal ca-:e only 31 > 1| : Sin. Fnily tunable — complete with 
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In metal case siie 4 s 6 x llin. Fully tunable— complete with PCSfi and 
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38 Mc/s. Contains a large number of components, IF trans- 
former*, resistors, capacitors etc., and the following valves: 
2 x PCF80, 1 x EB91, EF80, BP188 and EF184. Overall size 
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(above) provides a suitable conversion for BBC2. 
No circuit available. LASKY'S PRICE 29/6 Post 2/6 

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Free standing table cabinet, size 
191 x 9 x "''in-, finished in medium 
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(l.'HF band). Designed to accept the 
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CABINET ONLY 27/6 Post 3/6 

Special Package Oiler: IF Amplifier, 
till Timor wit h valves ami TableCabmet 





PACKAGE PRICE 59/6 ! 




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in conjunction with extreme small size and 

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n used throughout. All designed 
to operate on 9v. miniature battery. 
Add 1 - on each lor Post and Packing. 
TYPE LRPC 1. 3 transistor. Input sens. 
BOmY, output ISOniW, output Imp. 40Q, 

2xlxjin PRICE 27/6 

TYPE LRPC 2. 5 transistor. Input sens. 
lmV, output 330ui\V, output imp. 15Q, 

size 2i x li x Jin PRICE 22/6 

TYPE LRPC 3, 5 transistor. Input sens. 5mV. output 400mV. output imp. ISO. sliro 

2*xl|xSin PRICE 25/- 

TYPE LRPC 4. 5 transistor. Input sens. loOmV. output 330mW, output imp. Ifln, size 

2Jxl,x}ln. PRICE 22/6 

TYPE LRPC 5. 6 transistor. Input sens. SmV, output 3W, output imp. 3Q, size 

OJxlJxlln PRICE 59/6 

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Output 760 niW, output imp. 811. Size 4i x2 x lin PRICE 39/6 

FULLY ENCAPSULATED MODULES 

Special function modules — all one size 1 ; x 1 x I Jin. Complete with detailed function and 

installation instructions. Send S.A.E. for specification sliorus 

TYPE PA-1. Public address amp. for use with carbon, crystal or Dynamic mktropbanM 

3Q output Imp .',. PRICE 30/- 

TYPE GR-1. Gramophone amp. — provides sufficient power to fill average room. 3t> 

output Imp PRICE 30/- 

TYPE CO-1. Morse code practice oscillator— for use with morse key and 3fl speaker. 

PRICE 20/- 

TYPE MT-1. Metronome module — provides andible and visual beat from 30 to 240 beats 
per minute (for use with 3 Q speaker or indicator lamp) PRICE 22/6 

GORLER UT 340 FM/VHF TUNING HEART 

IVrmi uiiilty tuned — covering 87 to 10S Mc/s. For use with one ECC85 valve. In m-'tal 

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■ li -:■"':. '.IC2'.'.| 15/-: OC2ii.j. 'Ji-ji.-. 19>6: ■n-:- 2416: Qi'7.-, 8/-. 

TR AN S Fl LTE RS by BRUSH CRYSTAL CO., Available Irom stock. 
TO— OIB 468 kc/s. ± 2 kc/s. I TO — 02D 470 kc/s. + 1 kc/s. Q/fi o ar h 

TO— OlD 470 kc/s. ± 2 kc/s. TF— OIB 465 kc«. ± 2 kc/s. ' " cao " 

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LASKY'S RADIO FOR FINEST VALUE and COURTEOUS SERVICE 



728 



SERVICE IN GREAT RRITAIN 
ANR HI-FI ENTHUSIASTS 



Laskys 

RADIO 




RECORD PLAYERS 



BCD 

a'uto'changers 

AT LOWEST EVER PRICES 

Brand new and fully guaranteed — 
complete with cartridge and stylus. 

UA14 4 Hpecd mains inodel £4. 8.6 

UA16 4 speed mains mode) £4.19.6 

CA16 9v. battery model £5.19.6 

UA20 4 speed mains model £5.19.6 

Add B/- carriage and packing on each. 

NEW LOW 
PRICES I 
SINGLE PLAYERS 

SP25 Mono £9 19 6 

SP'25 Stereo £10 19 6 

SRP12 with cartridge £4 7 6 

SRP10 Mains, with cartridge. . £4 19 9 

8RP10 Battery, with cartridge £4 19 8 

GARRARD BASES 

WBl £3 16 3 aearvi.w coTor £3.10.0 
WB2 £5 5 CIcarviow cover £4.17.6 

■ Postage and Packing on all above 5/-. 

GREENCOAT RECORD PLAYER 

33'/, and 45 r.p.m. 6 v. Battery operated C'omp. 

LASKY'S PRICE 49/6 P 0rt2 /8 



GARRARD AUTOCHANGERS 



AT6 Mono £8 19 

AT6 Stereo £9 9 

3000LM with etereo cartridge" £7 9 

AT80 with stereo cartridge . . £10 9 

A70 less cartridge £19 9 

A5fl less cartridge £7 10 

A1000 with GC8 cartridge . . £6 6 

A2000 with GC8 cartridge . . £6 8 



th pick-up and crystal cartridge. 
Slie 7 J y 6ln. 



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THE X-20 20 watt P.W M. ampllfler '.'.'.'.'.'. '.'.'.'.'.'.'.'.'.'.'.'.'.'.'.', '. '. '. ', £? 19 6 

Available ready built, tested and guaranteed ,,,,,, VM . I" £9 19 8 

THE Z-12 12 watt amp. and pre-amp., fully built £4 fl A 

STEREO 25 Pr«.ftinr.lifkr control unit, fully btlQt . '. ',. . '.'.',".'..". .'.'.'.'.[', '. '. '.'.'. £9 19 6 

MARTIN HI-FI AUDIOKITS — — _ 

Using specially developed circuits, the very latest transistors and printed oircults— these 
kits are all fully checked and tested before leaving the factory. 

KIT 1. stage Matching Input Selector Unit LASKY'S PRICE £2/7/6 

KIT 2. Pre-anipllller with volume control LASKY'S PRICE £1/17/6 

KIT 3. 3-Channel Mixer, with plug-in adaptors for individually 

irrm . matching each circuit. Adaptors 8/6 each LASKY'S PRICE £3/19/8 

KIT 4. Pre-ampllfler with tone/volume control stages ...... LASKY'S PRICE £3/2/6 

10 and 3 watt Main Amplifier LASKY'S PRICE £5/12/6 

Power supply Converter Unit LASKY'S PRICE £2/12/8 

15 ohm version of Kit 5 LASKY'S PRICE £6/12/6 

Power supply for Kit 7 LASKY'S PRICE £2/15/- 

' i'^ I . Hea 2„---™,- LASKY'S PRICE £5 12 6 

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THE HARROW POWER PACK 

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ordering. 

LASKY'S PRICE 29/6 Post 2/- 



KIT5. 
KIT 6. 
KIT 7. 

KIT 8. 
UNIT 15. 



207 EDGWARE ROAD. LONDON. W.2 Tel. PAD 3271 

118 EDGWARE ROAD. LONDON. W.2 Tel. PAD 9789 

33 TOTTENHAM CT. RD.. LONDON. W.1 Tel. MUS 2605 

All the above branches open all day Saturday. Early closing Thursday. 



42 TOTTENHAM CT. RD.. LONDON. W.1 Tel. LAN 2573 

1 52/3 FLEET STREET. LONDON. E.C.4 Tel. FLE 2833 

Both open all day Thursday. Early closing Saturday. 



ail Orders and correspondence to 3-15 Cavell Street, Tower Hamlets, London, E.I. Tel.: STEpney Green 4821/2 



LASKY'S FOR SPEEDY MAIL ORDER SERVICE 



WEYRAD 



COILS & TRANSFORMERS FOR CONSTRUCTORS 

Special versions of our P50 Series are now available for AF1 1 7 or OC45 Transistors. They can be used in the standard 
superhet circuit with slight changes in component values, details of which are given in the latest edition of the 
Constructors' Booklet priced at 2/-. 



Oscillator Coil P50/1AC (For OC45) 

1st I.F. Transformer P50/2CC (For OC45) 

2nd I.F. Transformer P50/2CC (For OC45) 

3rd I.F. Transformer P50/3CC (For OC45) 



P50/1AC (For AF117) 5/4 

P51/1 (For AF117) 5/7 

P51/2 (ForAF117) 5/7 

P50/3V (For AF117) 6/- 



Rod Aerial RA2W 12/6 

Driver Transformer LFDT4/1 9/6 

Output Transformer OPT1 10/6 

Printed Circuit PCA1 9/6 

I.F. TRANSFORMERS & COILS FOR VALVE CIRCUITS 

Production of Tuning Coils (Type "H") and I.F. Transformers is being continued and details of these and our 
other components are given in an illustrated folder which will be forwarded on request with 4d. postage please. 

WEYRAD (ELECTRONICS) LIMITED 

SCHOOL STREET, WEYMOUTH, DORSET 



729 



stern-dyne 



ELECTRONIC CENTRES 



MEMBER 
OF THE 

PANT1YA 
GROUP OF 

COMPANIES 

MAIL ORDER & ALL ENQUIRIES TO: DEFT. PW. 3-6 EDEN GROVE. HOLLOW AY. LONDON. N.7 Tel. NORth 8161/5. 
LONDON: 9 Camberwell Church Street. S.E.5. RODney 2875 LIVERPOOL: 52 Lord Street. Royal 7450 

18 Tottenham Court Road. W.l. MUS 5929/0095 220 Edgwuro Road. W.2. PADdington 5B07 J£ A n .l C 55? T ^, R : „, . „, , . • ..-oleosa 

23 Tottenham Court Road, W.l MUSeum 3451 ""SI", ,„ . ' !, „ „ ™"™*""™' 20/22 Withy Orove, M/o 4. Blaoklnars 5379/5246 

309 Edgware Road, W.2 PADdington 6963 CROYDON : 12 Suffolk House. George Street. SHEFFIELD : 125 The Moor. Sheffield 29893 

109 Fleet Street, E.C. 4. FLEet Street 5812/3 MUMoipal 3Z50 NOTTINGHAM: Eastown House, Linooln St. 

162 Holloway Road, N.7. NORth 7941 BRISTOL: 26 Morohant Street, Bristol 1. Bristol 20261 Nottingham 45889 



SULTAN 

solid-state integrated 
Stereo amplfier 




The most advanced design in 

brilliant new kit form — so 

simplified you can build il to professional standard! 

without specialized knowledge ami with -iniplc tools. 

Designed for kit builders from the beginning with a system of wiring : hftt enables you 

to complete each solder joint as you proceed; nothing is soldered twice and there are DO 

unfinished joints left waiting bo overlook! 

SULTAN performance is a natural re.-ult of superb design incorporating the goal 

advanced fully proved semi-cnnd\K't..rs. ami modular substafractraitrootlontnal pi rmll 

searching qnalitv control and precise matching at every stage of assembly. Particular 

attention has been given to the provision of all the additional input . output . ami DOW" t 

take-off facilities ever likely to be required. The compact abed, .rnf t-nu.r. Bnbhl I ' ak 

cabinet and restrained styling ensures unobtrusive, harMOBlona matching with almost 

any decor. 

Sultan kit ol parts £29.8.0 Assembled and Tested £39.18.0 

Carr. i Iu~. Carr. 1 

Tenus: Deposit £9.16.0 and 1-2 monthlv pavments of fl.lii.lo. 

Total credit price £31.18.0. 
Terms: Deposit £13.6.0 and 13 tuunthlv payments of £2.8.10. 

Total credit price £42.12.0. 

• Descriptive leaflet free on requesji 

• Assembly Manual available separately I in.-l. P. * P. 



SEND FOR CATAL0 GU E 



A i;- P.O. brings new inu-pagc 
items: profusely illustrated. 



id Science Catalogue packed with uninue 




Kit ot parts £1 1 .0.0 
Carr. & 1ns. t 



lit 



Total oredit price £26.10.0 
* Ins. in- 



Designs by MULLARD 

inierpreted by 

STERN 



5-10 POWER AMPLIFIER 

One of the mast famous amplirters ever made — thousands are in use throughout the 
world. Superbly constructed to rigid stern-t .'lync requirements and conforming i 
to Milliard specification, including all specified component" and brand no* United 
valves. Auxiliary power take-off for pre-amp and tuner (230 volts and 40 niA and 
o.:» \--lts ai 2: A) and gram mains supply ou rear panel. 

Assembled and Tested £14.10.0 

Caw. .v In-, 'i 1 



2 VALVE PRE-AMPLIFIER 

Specially designed by Milliard Research Laboratories for use with the 5-10 amplifier 
and one" of the most compact pie Unpllueu available. Measuring only f>\ x 2! X 4}ln. 
deep. Inputs are provided lor variable reluctance and crystal pick-ups with RIAA 
equalization, plus radio, sensitive microphone and tape reply d ire, i ,..r fn.ui pre -ami lUflei 
Controls: B position selector, volume on oil, trtdi range haja and Inula, Powntao awed 
by 5-10 amplifier. 

Kit ol parts £6.6.0 Assembled and Tested £9.10.0 

Carr. & ins. 5/- Carr. A Ins. 5/- 

COMBINED PRICES „.„.„„ 

5-10 Amplifier with 3 valve pre amplifier complete k:t of purls £1>.16.0. 
Terms: Deposit £5.16.0 ami 12 monthly payments 01 £1.4.2. 

Total oredit price £20.6.0 

5-10 Amplifier and 2 valve pre-aniplilu r assembled and tested 
Terms: Deposit £8.0.0 and 12 monthly payments of £1.10.10 



RECORD PLAYERS AT ECONOMICAL PRICES 



BSR GTJ7 4-speed with X1H cartridge £3.19.1 

GARRARD SRP22 4-spoed with GP91 oartridge . . .. £4.10.1 

BSR OA25 4-speed autochanger with cartridge . . , . £5.19.1 

BSR DA50 Miniohanger less cartridge iB.lO.t 

GARRARD 1000 Antoohanger with GC8 cartridge . . £6. 6.( 

GARRARD 3000 Antoohanger with STH/HC cartridge £7.10.1 

GARRARD SP25 with GP91 oartridge £12.19.1 

Carriage and Insurance on above 5,- extra 

GARRARD 401 Transoription Motor £32.10.( 

GOLDRING GL68 Transoription unit less oartridge . . £19.16.1 
GARRARD LAB80 Transcription Autoohauger less 

cartridge £24.19.1 

GOLDRING GL70 Transoription unit loss oartridge . . £30.7.1 
Carriage and Insurance on above 7 6 extra 



PC1 




PORTABLE GRAM CASES 



Dpi For record plaver Installation only and ideal for use with portable PA systems 
rv *' and radio set amplifiers. Takes all standard single players and autochaugers. 
Bin ■'■■■ rail: Hi s 14 x 8{in. Includes uncut motor board, size 15i x 13im.; height 



;.in 



:16: 



pro Suitable single players and amplifier/speaker installation. Size overall: 18 : 

ft} in. Board size 152 I 1.1 J in- wit li Sin, clearance below board; height above 2jin. 

Cut out- an- provided to li: the Stern-dyne Monogram amplifier and 8 x 5in. speaker. 

Suitable for liarrnrd 8RP22 Record Player, or similar unit. 

pp-J For autochanger. amplifier/speaker Installation. Size overall: 18 x 16 x Sin. 
Hoard size 151 x lUitn.. with 2* Is in. clearance below board; height above 4Jin. 

Will also accommodat e Si ern-i 'Ivnc Mononrani amplifier, 8 x 5in. speaker and all stand- 

aid Aufooaangen, 

Add B/6 Carriage and Insurance (or any nf above. 



MONOGRAM AMPLIFIER 



Boperfa -pace and cost economy design 
-peiiaiiy ii< retoped by Milliard R esearc h 
U-lmralnrien and quality co nstruc ted by 
Htorn-Clyne. Actually u-e- only otM uoilii 
valve but provides an undistorted output 
from any standard xtal pick-up. Plus 
include B»j« Boo^t and Treble 
controls, panel illumination and specially 
u.-und output transformer. Size only 
lin , Jin. high Silver hammer 
chassis finish satin silver finish engraved 

Descriptive leaflet Iree on request. 




Kit ol parts 
Carriage 4:6 



£5.0.0 

Assembled and Tested f 7 Q R 
Carriage 476 L1.3.U 




Complete kit ol parts 
Assembled and tested 



STERNKIT FM1 
TUNER 

A new specially designed sensitive tuner 
lor the amateur builder. Provides a 
-table, iiuerierence-free reception of 
i.iii I'M transmissions. High quality 
output signal ensures optimum . per- 
■ irorn any ni-Fi audio system. 
Reliable easily aligned circuit includes 
RF stage and 2 IF noise limiting stages. 
Input sensitivity hetter than 100 micro- 
volts fur 40dB quieting. Power requin r- 
in. -Hi- 200 volts at 25mA. R.avoltsat 1.5A. 

£7.9.6 



£10.9.6 



Carr. A- Ins. 4/- 
Carr. * Ins. 4/- 



Optioual 
Assembled 



power pack Type D kit £2.15.0 Carr. 3/6 Assembly Manual only 3 '- 

pi 4 n n post iiee ~ 

and tested L J . I U ■ U f -arr. :-> 'i Desoriptive leaflet Iree on request 



VM 39 x 6 TEST 7 Pocket Multimeter 



Carr. 21- 




A reallv versatile instrument that makes a handy pocket- 
size tool. Measures AC or DC voltage in three ranges of 
O-lo-150-lOOOv. Resistance 0-1000,000 ohms and Current 
0-lSOinA. DC. Size only 38 x 2! x lfln., with ingenious 
dial design providing a clear, easily read scale. Complete 
With battery and teat leads. 



TERMS AVAILABLE ON ALL ORDERS OVER £15 IN VALUE 




OUR FINEST EVER METER VALUE! 
DUVIDAL IT1-2 MULTITESTER 

With Built-in Meter Protection! 

Pocket size with wide-angle, jewelled meter movement, 
ceramic long-life, low-loss switching, tough impact 
resisting case. Sensitivity 20.000 ohms/vtilt DC. 
10,000 ohms volt AC. 

19 Ranges measure: 

0—5—25—250 500—2500 volts DC. 0-10-100-500- 
1000 volts AC. 0-50 uA— 2-5 mA-250 mA DC. 
0—6000 ohms— 6 megohms. 10 u-f— 0-001 mA— 1 
mfd.— 20 to + 22 dB. 



730 



PRACTICAL 

WIRELESS 



VOL 42 No 10 



issue 720 



FEBRUARY 1967 



TOPIC OF THE MONTH 
Troubled Waters 

THE first blow was struck against the radio 
'pirates' on Friday, 25th November, 1966, when 
Radio 390 were fined £100 for using a transmitter 
without a licence, at Red Sands Tower on 16th 
August, 1966. Mr. Edward Allbeury and Mr. David 
Beresford Lye, directors of Radio 390, who were 
found guilty of the same offences, were each given 
an absolute discharge. 

The second blow came just five days after the 
Radio 390 case, when Mr. Roy Bates, proprietor 
and operator of Radio Essex (now known as Radio 
BBMS) was fined the maximum of £100 at Rochford 
Magistrates' Court, Southend. Both 'pirate' radio 
stations are to appeal against the findings. 

Radio City who also operate from one of the 
war-time forts in the Thames Estuary have not so 
far been prosecuted under the Wireless Telegraphy 
Act of 1949 for illegal broadcasting. On the findings 
of the Canterbury and Rochford Magistrates (court 
reports inside), Radio City is within territorial waters 
and it would appear that the Crown could get a 
conviction. So why have they been missed ? Could 
it be something to do with ownership, or is it that 
they are not big enough to worry about? 

Radio BBMS has openly defied the Government 
by continuing to broadcast from Knock John Tower 
in the Thames Estuary, and Radio 390 admits that it 
will broadcast from another country on the Continent 
if it loses the pending High Court appeal. 

The Marine and Broadcasting (Offences) Bill will 
give the Government powers to silence all the 
'pirates' in one swoop when it becomes an Act of 
Parliament. But, how long is this going to take? 
The Government have many Bills on the Statute Book, 
a number of which they consider to be of more 
importance. However, even this legislation cannot 
prevent commercial operators setting-up high power 
stations on the Continent, which could be beamed 
to this country. 

Realising that the Marine and Broadcasting 
(Offences) Bill is already in the pipeline, was it 
worth prosecuting Radio 390 and Radio Essex? 
The first case took two days to hear and the second 
one a full day, and cost us — the tax-payer — hun- 
dreds, if not thousands, of pounds sterling. 

W. N. STEVENS, Editor. 



NEWS AND COMMENT 



Leader 

News and Comment 

Radio 390 and Radio Essex 

Court Cases 
The MW Column 

by Alastair Woodland 
Practically Wireless 

by Henry 
On the Short Waves 

by John Guttridge and David 

Gibson, G3JDG 765 

Club Spot — Fareham and District 

Amateur Radio Club 781 

New Books 782 



731 
732, 760 

740 

742 

762 



CONSTRUCTIONAL 

A Short Wave Preselector 
by A. S. Carpenter, G3TYJ 

Transistorised Computer 
by S. Benda 

Preampfor Dynamic Microphones 
by A. S. Ellis 

Push Pull Neon Driver 

by A. J. Bassett 
Receiver for 144Mc/s 

by F. G. Rayer, G30GR 
Wide Range Signal Generator 

by R. F. Graham 
Pulse Counting V.H.F. Receivers 

by D. V. Debbage 

GENERAL ARTICLES 

The Home Workshop 

by G. T. Theasby 
Power Supplies 

by H. J. Kitchen 



734 
737 
745 
752 
753 
756 
774 



MARCH 



ISSUE WILL BE PUBLISHED 
FEBRUARY 3rd 



749 
777 

ON 



All correspondence intended for the Editor should be addressed to: The Editor. "Practical Wireless", George Newnes Ltd.. Tower House. Southampton Street. 
London. W.C.2. Phone: TEMple Bar 4363. Telegrams: Newnes Rand London. Subscription rates, including postage: 36s. per year to any part of the world. © George 
Newnes Ltd., 1967. Copyright in all drawings, photographs and articles published in "Practical Wireless" Is specifically reserved throughout the countries signatory 
to the Berne Convention and the U.S.A. Reproductions or imitations of any of these aro therefore expressly forbidden. 



731 



Imported Communications 
Receivers 

It has come to our notice that a letter 
appeared in the December 1966 issue of 
Practical Wireless stating that service 
and spares were not available for im- 
ported communication receivers. 

We sell considerable amounts of im- 
ported communication receivers, many 
through the medium of advertisements 
in this magazine, for all of which we 
carry spares and have full servicing 
facilities. 
G. W. Smith & Co. 3 Lisle Street, 

London, W.C.2. 

[As you are probably aware, these 
servicing and spares facilities are not 
always available from radio dealers, 
which inspired the letter from a reader. 
We are glad, therefore, to hear that at 
least one company is able to offer such 
facilities.] — Editor. 



Buy British? 

I have a Lafayette catalogue which 
shows several models of the H.E. range 
of receivers and all are quoted as being 
"imported" into the U.S. So that those 
on the U.K. market are presumably re- 
exports from the U.S. 

I have also been called upon to repair 
a Sharpe radio of Japanese manufacture 
which was purchased in Hong Kong and 
have found that the valves used cannot 
be purchased in the U.K., there are no 
equivalents and that letters to agents in 
Japan and Germany have not produced 
any results. 

I agree with Mr Pryse, one must by 
very careful what one buys. But beggars 
cannot be choosers; after all, what 
British sets are available at such mod- 
erate cost as the Jap jobs with the same 
specifications? 

A. Parry. South Oxhey, 

Hertfordshire. 



Transistor Terminology 

I used to use valves. However, I have 
now graduated to transistors. What an 
utterly wretched mess. Every manufac- 
turer has his own numbering system and, 
it would appear, his own set of nota- 
tions. One maker's Ico is another's 
Alpha dash, and mistaking one manufac- 
turer's beta for another's hybrid pi can 
cause a very nasty accident. How about 
all the "big-boys" sitting round a table 
and settling on a simple standard nota- 
tion we can all understand? 
Martin Jessopp. Leyton, 

London, E10. 



NEWS AND. 



A.A. MEMBERS GO ON THE AIR 
The world's first 24-hour two-way v.h.f. car radio link between 
a motoring organisation and its members on the road — the 
A.A. Linkline Service — has been introduced. Under the new 
service, A.A. members in and around London and Birmingham 
and travelling up theM1 will be able to keep continuous two- 
way contact with A.A. operations rooms and will be able to 
radio direct for the breakdown service, pass urgent messages 
to and receive messages from anyone, receive warnings of 
traffic jams etc., obtain weather reports and even find out the 
correct time. Linkline rental of £180 per year includes all 
equipment and installation costs, set hire, licence fees, servic- 
ing, all radio calls and certain emergency calls connected with a 
breakdown or accident. 

COURSE ON AMATEUR RADIO THEORY AND PRACTICE 

Interested persons are invited to find out more about a proposed course 
on Amateur Radio and Electronics, to begin shortly. The course will 
be held in the London Borough of Waltham Forest, and is designed for 
those who missed the beginning of the normal courses, or who find the 
location of the R.A.E. courses difficult to reach. 

The scheme should be suitable for persons wishing to try the Winter 
1967 Radio Amateurs' Exam and for persons who would like to brush 
up on the subject. Young people and beginners will be made very 
welcome. K. L. Smith, G3JIX, 82 Granville Road, Walthamstow, E.17. 

NEW LOW PRICED F.M. PORTABLE 




H. O. Thomas Electronics announce two new models, bringing their 
total range of Wien radios up to six. They are the Wien "Sport" retailing 
at 7 2 - guineas and a mains/transistor am/fm set — the Ml — at 16 
guineas. 

The M1 is a table model in teak cabinet, embodies 8 transistors, 
covers medium and f.m. bands. The "Sport" (see photograph) covers 
f.m. and medium waves, has 9 transistors and comes complete with 
earpiece, strap and batteries. Further information from H. O. Thomas 
Ltd.. 4 Vernon Place. London. W.C.I. 

SCHOOLBOYS AND GIRLS EXHIBITION 
Opened in the Empire Hall, Olympia on December 27 this 
exhibition features among its exhibits a TV videotape studio 
presented by Ampex Ltd., where children are able to mime an 
action or play a charade and see their performance played back 
immediately on a TV monitor screen. 



732 



. COMMENT 



GRUNDIG A.F. SIGNAL TRACER 




Among the new Grundig range of test instruments is the SV2 a.f. signal 
tracer. The use of transistors and battery operation make the instrument 
ideal for lab. or field work. The test probe type UK2 supplied is switch- 
able between a.f. and r.f. In the r.f. position, it operates as a demodulator 
for frequencies between lOOkc/s and 300Mc/s whilst the low capacity 
ensures no detuning of the circuit under test. 

Frequency response is 200c I s to 8kc/s -3dB. Input for 160mW 
output in the OdB position is ImV and in the -40dB position 100mV. 
Input impedance is 500. on the OdB position and 5MD, in the -40dB 
position. Output voltage is 0-9V and output impedance is 1kO.. For 
further details contact Grundig (Great Britain) Ltd., Newlands Park, 
Sydenham, S.E.26. 

SAIMSUI PRODUCTS 
Lasky's Radio Limited have now been appointed sole distri- 
butors in the U.K. for Sansui High Fidelity equipment. 

The range comprises a complete selection of high quality 
stereo amplifiers, tuners and combined tuner/amplifiers. 

Price list and details are available on application to Lasky's 
Radio Limited, 3/15 Cavell Street, London, E.I. Demonstrations 
can be provided at 42 Tottenham Court Road, London, W.1. 

10,000 POLICEMEN TO HAVE POCKETPHONES 

A major contract worth £500,000 has been awarded by the Home 
Office to Pye Telecommunications for the supply of Pocketphone u.h.f 
transceivers. One hundred police forces will shortly be using these units. 

TWO ADDITIONS FOR LEKTROKIT 

A.P.T. Electronic Industries Ltd., Chertsey Road, By fleet, Surrey, 
announce the availability of Chassis Plate No. 7 and Insulator Lead- 
through No. 2 in the Lektrokit Chassis Construction System. 

Lead-through insulators are connection devices for insertion into 

the Lektrokit No. 7 chassis 
plate for circuit wiring. 
They are made of PTFE 
high grade insulant and 
the Sealectro "Clover 
Leaf" connection insert, 
which provides a multi- 
aperture insulated termin- 
al point for use in circuit 
wiring on metal chassis 
and provides five con- 
nect/on wires. Price of 
No. 7 Chassis Plate is 
12s. per pack of 2 and 
No.2 Insulators, 3s. per 
pack of 6. 



Illfiill 






-, . 




Way-Out Style 

As a young boy I was always being 
caught out by my elder sister. She 
would plague the life out of me with a 
series of classic "When is a so-and-so 
not a so-and-so". As the years drifted 
merrily by I came to be free of these 
irritating conundrums, and indeed I had 
forgotten all about the wretched things 
until I started to read Practical Wire- 
less and then, bless me, there they were 
again. I refer to these drifting standards 
which never seem quite what they are 
supposed to, and vary from one designer 
or advertiser to another. Take signal to 
noise ratio. Now there's plain signal-to- 
noise, or there's signal-to-noise-plus- 
noise and so it goes on with a few hand- 
fuls of dB's thrown in for good measure. 
Audio amplifiers are notorious for this 
sort of treatment. Not only do we have 
noise figures (no mention of the sig- 
nal now, only the noise), we have 
hum, input sensitivity, outputs, im- 
pedances and Uncle Tom Cobley ad 
infinitum. Of course all this information 
may be very useful but the standard 
references to which all these figures are 
referred seem to alter with each item one 
reads about. One manufacturer assures 
that his amplifier will supply 12 watts 
output. Now a friend of mine bought 
one of these and. as he worked as an 
apprentice in an electronics laboratory, 
took the unit in for a test. It was found 
that the unit actually provided four 
watts output. These results were 
checked by a senior member of the 
staff, and I have no doubt that the tests 
were valid. So how about a definite 
standard rating on these things to which 
all units are related. Then when we buy 
a ten watt audio amplifier we will get 
ten watts and not five or two. These 
glowing adjectives beloved by advertis- 
ing agents should be made to be 
accurate. Could not the magazine accept- 
ing the advert check first? II you raise 
anything with the advertisers they 
invariably blind you with science. "Ah, 
that's under quiescent conditions, and 
assuming that the signal does not exceed 
one millivolt, of course you could cal- 
culate for the input transistor bottoming 
but then the hum level will be up by 
about, Ooh let's see now 25, yes about 
25dB so you can't have it both ways 
can you?" So how about some stan- 
dards and every one sticking to them. 
At the moment I'm back in my child- 
hood memories again. When is a 12 
watt amplifier not a 12 watt amplifier — 
when it's advertised as such? 

R. Farjohn. Kettering, 

Northants. 



More News and Comment on Page 760 



733 



O PRESELECTOR ? 



A. S. CARPENTER 



3 



ft 




o 

x 




</> 



G3TYJ 



THE practical preselector design to be described 
is continuously tunable over the frequency 
range 14 — 30Mc/s thereby embracing the three 
high frequency Amateur bands, viz., 10, 15 and 20 
metres. 

The prototype preselector is used primarily in 
c.w. connections; it is attractive physically and may 
be powered from the station receiver. Tuning is 
carried out via a slide-rule type drive with '10* and 
'20' occupying the scale ends. Ample space does 
exist for the inclusion of a small mains transformer 
plus rectifier circuit capable of supplying 200-250V 
d.c. at 20mA and 6-3 V a.c. at 1A. 

It is desirable to be able to mute the preselector 
when an associated transmitter is to be used nearby, 
and a self-shorting jack-socket is fitted via which a 
muting circuit may be introduced. The preselector 
may be muted very conveniently, either fully or 
partially, by arranging for a 50kfi variable resistor 



Tl base 


03 40 

O 

01 60 




to be automatically switched in and out of circuit 
by the transmitter 'Send/Receive' switch. No pro- 
vision is made for bypassing the unit — by means 
of a switch perhaps — since this is carried out 
manually. 

Some communications-type receivers used at 
Amateur and SWL stations use valves that are con- 
sidered to be 'noisy' by modern standards; by using 
a preselector between the aerial and the receiver a 
considerable improvement results particularly on 
the higher frequency bands. This is understandable 
since when a strong signal is fed to a "noisy* 
receiver the a.v.c. system is loaded adequately and 
the valves are biased back heavily; the received 
signal then sounds clean and 'punchy*. It should 
be noted however that a preselector should not be 
considered as an alternative to a good aerial but 
merely an addition. 

The complete circuit diagram is shown in Fig. 1 
where VI functions as a 
high-gain r.f. amplifier with 
V2 operating as a con- 
ventional cathode-follower 
output stage. The station 
aerial is plugged in at 
socket Ski, either direct or 
via the transmitter/receiver 
change-over switch or 
relay, and a short screened 
lead from socket Sk3 is 
connected to the receiver 
aerial socket. Band cover- 
age is effected by means of 
VC1, the shaft of which is 
in connection with the 
panel-fitted drive and scale. 
Variable r.f. gain results 
from fitment of VR1. Amp- 



Fig. 1: The theoretical circuit 
diagram. 



734 



lified r.f. appearing at pin 7, VI 'sees* consider- 
able opposition from the r.f. choke whereupon it 
passes more readily to the cathode-follower output 
stage via capacitor C5 to re-appear at socket Sk3. 
Normally the anode circuit of VI is operated in 
a non-resonant state, grid circuit tuning being 
adopted. Extra gain may be obtained however by 
resonating the anode circuit close to the operating 
frequency and to this end coil LI and panel-fitted 
VC2 are provided. Although, in theory, maximum 
gain occurs when both grid and anode circuits are 



RFGain 



II 



Tuning! 



I Peak 




Moving plates 
connect to 
chassis 



Fig. 2: Above-chassis layout and dimensions. 



tuned to the same frequency such exact tuning is 
rarely practical since oscillation takes over. Under 
certain conditions — maladjustment of VC2 for 
example — oscillation can be instigated; it becomes 
very important therefore to include adequate screen- 
ing. In the prototype the 
grid and anode circuits of 
VI are well screened from 
each other: a 'can' is fitted 
to Tl and the chassis box 
is also made use of. 
Screening is indicated by 
the broken lines in Fig. 1. 

Normally VC2 is set to 
minium capacitance and is 
used only under difficult 
copying conditions. The 
circuit is useful cw.-wise 
for as VC2 is manipulated 
tuning tends to sharpen 
due to positive feedback. 
The benefits are somewhat 
less apparent on 'fone' for 
the extra gain secured is at 
the cost of an increased 
noise level. In this part of 
the circuit it should be 
noted that capacitor C9 is 
a d.c. 'blocker' and it must 
on no account be omitted! 

The layout and most of the wiring is shown in 
Figs. 2 and 3. No chassis drilling diagram is given 
since constructors may vary things to suit items to 
hand. The type of capacitor used for VC1 for ex- 
ample is not over-critical and any small single- 
gang item of about 150pF maximum capacitance 



associated with Tl are bent outward (not inward) 
to permit the can to be removed without disturb- 
ing the coil itself. 



Coil Details 

Both Tl and LI are home-brew dust-cored 
items. Considering Tl, and assuming approximately 
30pF for circuit 'strays', a tuned circuit inductance 
of some 0-9,"H used in conjunction with a 150pF 
variable capacitor will enable the desired band 
coverage to be obtained. Tl consists of 10 turns 28 
s.w.g. enamelled copper wire close wound on a 
0-3in. former, and 6 turns of 36 s.w.g. d.s.c. copper 
wire close wound, for the aerial winding. The two 
windings are separated from each other by 0-05in. 
LI is 12 turns of 28 s.w.g. enamelled copper wire, 
turns close. Later, a turn per coil may need to be 
removed to ensure correct band coverage, coils 
being tested either by using a g.d.o. when they are 
in situ, or via received signals. When finding the 
frequency range afforded by the T1/VC1 combi- 
nation with a g.d.o. it will normally be necessary 
to remove the screening can although it should be 
remembered that re-fitment of this will cause the 
circuit to resonate at a slightly different frequency 
to that measured. Fortunately the dust cores per- 
mit considerable inductance variation. 

The size of the chassis used is also shown in 
Fig. 2 but when self-powering items are to be used 
this should be made 2in. longer. 

Details regarding the front panel are given in 
Fig. 4, matters being so arranged that when the 
completed assembly is placed on the table the front 
panel slopes backwards slightly to assist operation 
of the controls; the appearance also benefits. 




is suitable. Note in Fig. 2 that the lugs of the can 



Supplies via PL1 

Fig. 3: Wiring and layout below chassis. 

Casing details are given in Fig. 5 to agree with the 
prototype which is fashioned from faced hardboard 
and held together with pins and impact adhesive. 
When the preselector is not self-powered a suit- 
able power pick-up socket should be fitted to the 
main receiver. An international-octal (I.O.) valve 
holder is ideal for the purpose rigidly situated so 



735 



!0 



si 




PEAi?vT 



1/^ ^riTV ppOWER ON 
I f ' 



7 

Escutcheon 
outline 



Holes for controls 
are ^'dia. 

S^RFGAIN 



Fig. 4: Panel details. 
Fig. 5: Dimensions of the main casing. 




that plug Pll carrying the 3-core supply cable 
from the preselector can be engaged. 

Tests should then be carried out, using an 
ohmmeter, to ensure that no h.t.-chassis short circuit 
exists after which a short screened lead from socket 
Sk3 may be connected to the receiver aerial socket. 
The receiver may have separate aerial/earth sockets 
in which case the braid of the screened cable should 
be connected to the earth socket and the lead 
associated with capacitor C7 connected to the 
aerial socket. The receiver is then switched on and 
this will bring the preselector warning lens to life. 

Alignment 

A weak signal is now sought around 14Mc/s and 
the preselector pointer moved fully right to com- 
pletely enmesh the vanes of VC1. The vanes of 
VC2 should be fully disengaged and the dust core 
of LI removed. The core of Tl should next be 
carefully adjusted to increase the strength of the 
signal tuned using the receiver 'S' meter as a 
visual guide. 

The receiver is now tuned to the 15-metre band 
and a weak signal sought, after which the scale 



pointer of the preselector is moved toward mid- 
scale — or to where the signal sounds strongest. The 
same procedure is adopted on the 10-metre band 
when the preselector pointer should be almost 
fully to the left of the scale for maximum received 
signal strength. 

Should it seem however that the preselector can- 
not be tuned down far enough to peak the signal 
then too much inductance is in circuit and the 
core of Tl — or the number of turns — requires 
adjustment. Without the aid of frequency measur- 
ing gear some experimenting is inevitable but the 
aim should be to get '10' and '20' peakable at the 
opposite ends of the preselector scale. VC1 plays 
a major part in the band coverage and an electri- 
cally over-large item is undesirable. Where a good 
quality variable capacitor is to hand but which 
possesses excess capacitance, a fixed-value item may 
be wired in series with it. For example a 250pF 
variable may be suitably 'reduced" by including a 
470pF capacitor in series with it — or, alternatively, 
vanes may be removed. 

When the Tl/VCl combination has been dealt 
with attention may be given to the 'Peaking' cir- 
cuit, L1/VC2. The core should be lightly inserted 
in the coil and first tests made on "20' as before. 
The normally weak signal, already being amplified 
by the preselector should be further peakable as 
VC2 is carefully rotated when LI is of the correct 
inductance value. 

Although signals are likely to be heard at almost 
any time of day or night on '20' none may material- 
ise on '10', or even '15' for lengthy periods solely 
due to unfavourable propagation conditions. ■ 



• components li 



Resistors: 

R1 39kf> 
R2 6-8k£2 
R3 27D 
R4 1000 
R5 100kQ 
R6 22012 
VR1 5kDpot. 



Valves: 
V1 EF183 
V2 EF80 



(Lin.) 



Capacitors: 

C1 10,000pF ceramic 
C2 10,000pF ceramic 
C3 2000pF ceramic 
C4 10,000pF ceramic 
C5 50pF silver mica 
C6 2000pF ceramic 
C7 5000pF ceramic 
C8 4^F electrolytic, 350V 
C9 2000pF ceramic 
VC1 150pF variable (see text) 
VC2 100pF variable 
Jackson 'Air tune' 



Sockets: 

Ski i Sk3 — Coaxial type, surface mounting 

Sk2 — Miniature closed-circuit jack type 

Dial and Drive: 

Jackson type SL16 5191 complete 

Miscellaneous: 

R.F. choke, 2-6mH (Denco type RFC5), 0-3 in. 
Bakelite coil former with dust iron core and screening 
can (Denco Ref. 5000A/4PL), Coil former with dust 
iron core (Denco — Ref. 351 /8BA), Miniature panel 
lamp (Eagle PL), Octal plug. Knobs (3), Valveholders 
B9A (2), Chassis 7 x 3J x 1^in. etc. and casing 
materials. 



736 



TRANSISTORISED COMPUTER 

THIS computer uses 20 transistors and 30 
diodes. It adds and subtracts, the number input 
being fed in by a 'phone dial. The answer is 
read off 10 light-bulbs, which are mounted on top 
of the case. The answer is of course in binary 
form, with which the constructor should become 
familiar. The unit is small compared to anything 
else of similar function. 

Theory 

The computer consists of 10 bi-stable circuits 
called flip-flops, and the circuit of one is shown 
in Fig. 1. The circuit works in the following way. 

Suppose that Trl is conducting and therefore 
Tr2 is cut off, almost all the supply voltage will 
be across Rl and B. This means that the collector 
of Trl is nearly at earth potential. However the 
colleotor of Tr2 is nearly 12 volts negative. This 
means that Dl has only a small negative voltage 
across it in the reverse direction, but that D2 has 




Fig. 1 
Fig. 2 



(Above) Circuit diagram of one flip-flop. 
(Below) Pulses at points in Fig. 1. 

o 



Base Trl and Tr2 



Collector Trl 



Collector Tr2 




S. BENDA 

nearly 12 volts across it in the reverse direction. 

Now suppose that a positive pulse appears across 
the input bar. The pulse will not overcome the 
12 volts across D2, but it will overcome the small 
negative voltage across Dl. Thus Dl will conduct 




Tr6 



Fig. 3: (Above) Block schematic of "Adding". 

Fig. 4: (Below) Block schematic of "Subtracting' . 




Tr6 



and since the pulse is positive it will reduce the 
base current of Trl. 

This will reduce the collector current of Trl 
which will make its collector more negative. This 
increases the base current of Trl. Thus the col- 
lector current of Tr2 increases making the negative 
voltage on it decrease. This decreases the base 
current of Trl, until it is cut off and Tr2 is 
conducting. Fig. 2 shows the voltage wave forms in 
the flip-flop. 

N.B.: Negative pulses at the input of a flip-flop 
have no effect upon it, since they reinforce the 
reverse negative voltage across Dl and D2. In 
Fig. 2. 

To begin with, the bulb B, which is connected 
to Trl, is not conducting. A pulse in the base 
switches it on. Another pulse switches it off and 
so on. The collector of Tr2 is, of course, always 
in the opposite state to the collector of Trl. So it 
can be seen that a flip-flop can be represented by 
a little box with a bulb on top of it. 

It needs two pulses to switch the bulb through 
a whole cycle. This shows that the number of 
pulses which can be obtained from either of the 
collectors of a flip-flop is exactly half those appear- 
ing at the input. This can be verified from Fig. 2. 
Because each flip-flop divides the number of 
pulses by two, in the computer each flip-flop will 
represent twice the number of the preceding one. 

So if F.F.I represents one, F.F.2 will represent 
two, F.F.3 will represent four and so on. In the 
actual computer there are ten flip-flops so that the 
last flip-flop will represent 512. In Fig. 3 there 
are, for the sake of simplicity, only three flip- 
flops. The input of each flip-flop (except for the 



737 




Reset bar- 



IS 



32 



64 



123 



256 



5i2 



f 1 ' i ' 1 i i f- 



Fig. 5: Block schematic of the computer. Each box represents one flip-flop as in Fig. 1. 



first one) is connected to the preceding collector 
corresponding to Tr2 in Fig. 1. 

Suppose we start with all the bulbs off, in other 
words nought. If we dial a pulse into F.F.I this 
will switch on Bl. A negative pulse will be sent 
to F.F.2 (since the input of F.F.2 is connected to 
Tr2) and nothing will happen to F.F.2. We have 
added nought plus 1. Now if we dial another pulse 
into F.F.I we will switch BI off. However a posi- 
tive pulse will be sent to F.F.2 and this will switch 
on B2 which represents 2. We have added 1 plus 1 . 

The reader will then be able to work out for 
himself, that it is possible to add up to 7 on this 
circuit, but upon adding 7 plus 1, he will get the 
answer of nought. The actual explanation of this 
is that if there were a fourth flip-flop a positive 
pulse would be sent to this, registering the 
number 8. 

Fig. 4 is similar to Fig. 3 except that it is con- 
nected for subtracting. The input of each flip-flop 

is connected to the pre- 
ceding collector corres- 
ponding to Trl in Fig. 
1. Suppose we start 
with the number 7, 
that is all the three 
bulbs on. If we dial a 
pulse to F.F.I, Bl will 
be turned off and a 
negative pulse will be 
sent to flip-flop 2, B2 
and B3 will be left on 
corresponding to 2 plus 
4 which is 6. We have 
subtracted 1 from 7. 
If we dial in another pulse we will switch on 
Bl. This will send a positive pulse to F.F.2. This 
will switch B2 off which will send a negative pulse 
to F.F.3. So B3 and Bl will be left on correspond- 
ing to 4 plus 1, which is 5. We have subtracted 
1 from 6. Thus, to sum up, we have seen that: 

(1) A flip-flop is a circuit which can only be in 
two states, on and off. 

(2) A flip-flop effectively divides the number of 
pulses appearing at its input by two. 

(3) If a number of flip-flops are connected 
together, the number of each flip-flop is twice 
that of the preceding one. The total on the 
computer is of course obtained by adding 
together the corresponding value of all the 
bulbs which are on. 

(4) The flip-flops can be connected in an adding 
circuit or a subtracting circuit depending 
upon whether the input of each flip-flop is 
connected to the collector corresponding to 
Tr2 or Trl, in Fig. 1 of the preceding flip-flop. 




+12V D.C. 



Fuse 
Fig. 6: 



Suggested 
supply. 



power 



Construction 

Details of construction are left to the individual 
constructor since there are numerous variations 
and these are simple enough to work out. The 
recommended order of construction is as follows: 
the case is built, the power-pack is made, the flip- 
flops are constructed. 

Note: A reset bar is included. This makes it 
possible to set the computer to zero just by press- 
ing a switch. D3, in Fig. 1, is included in each 
flip-flop so that the flip-flops do not interfere with 
each other. 



The case 

It is clear from the size of the bits which ones 
fit on top of each other. The first step is to glue 
and nail A, B, C and G together. A, B and C are 
all made from £in ply, A and B being identical. 
When these have been assembled, D, E and F are 




Material: 
3/i6 thick 
plywood 



Fig. 7: Constructional details of the case. 

bracketed together by aluminium strips to the 
shape which they will have when screwed to the 
sides. 

Next, two flip-flops are constructed on a single 
printed circuit board. The lay-out of the flip-flops 
is left to the constructor. The printed circuit board 
is divided roughly in half and each flip-flop is con- 
structed in it. The earth bar, the negative supply, 
the output to the two bulbs, and the reset bar are 
connected to the connections which go to the 
sockets. 

The sockets which are the mechanical suspen- 
sions for the flip-flops are screwed to the back F 
about an inch apart from each other, starting an 



738 



inch inside the left side. The bulbs are then 
mounted on the top E. The connections to the 
appropriate bulbs are made from the plugs con- 
necting the extreme right plug to the extreme right 
bulb. This will be the first flip-flop, so that the 
numbers will go up from right to left as is conven- 
tional. All the bulbs are connected to the negative 
bar. Switch S is a push to test switch, used to reset 
to zero. 

Fig. 5 is a schematic diagram of the computer. 
When the five plugs have been wired together and 
to their appropriate bulb connections, only the 
negative and positive bars which go to the power 
pack will be left. There will also be the connec- 
tions to the switch which will be wired later. 

The reset switch S and the phone dial circuit 
are wired in as shown in Fig. 6. The phone dial 
circuit is so designed that it feeds positive pulses 
into the first flip-flop by breaking the negative line 
from the input. (The phone dial is normally shorted 
but when dialling, it opens.) The reset switch is 
mounted roughly in the middle of D in Fig. 5. 



• components list 



Resistors: 








ri ioon 




R6 


12kfi 


R2 220Q 




R7 


1-2kO 


R3 10kfi 




R7 


1-2kQ 


R4 10kQ 




R9 


10O 


R5 12kQ 




R10 


33ktt 


Capacitors: 








C1 0-05/iF, 


30V 


C2 


005 M F 


Semiconductors : 






Tr1 OC81 




D2 


0A81 


Tr2 OC81 




D3 


OA81 


D1 OA81 








Bulbs: 6V0-06A 







The above parts are those required for one flip-flop 
unit. Therefore, ten of each item listed above are 
required. The resistors are all £W 10%. 

Other parts: 

Ten bulb holders. Five transistors printed circuit 
panels (Radiospares). One 12-pole 2-way switch. 
One telephone dial. One 12V 1 A transformer. Four 
silicon diodes (at least 50V peak reverse voltage and 
1 amp). One 1,000/xF 15V capacitor. One 1 amp fuse. 
Five edge connectors for printed circuit panels. 



PRACTICAL TELEVISION 

A TV COIN SAVER. An ingenious but 
simple device which needs a coin in the 
slot before you view. No modifications to 
the set and will work with any model. 

MULTIPLEXER. Make your single -trace 
'scope into a double-beam unit. 
INTERPRETING SYMPTOMS. A simple 
guide to fault finding by observation and 
common sense reasoning. 
February issue of Practical Television is on 
sale January 20th, price 21- or 29/- per 
year post paid to any part of the world. 




jgraph of the comp 



type computer. 



The next thing to do is to construct the power 
pack in the right hand corner of the case. 

The first printed circuit (the first two flip-flops) 
is plugged in and the input to the first flip-flop 
is wired up. The power supply is connected and 
switched on. The bulb of the first flip-flop ought 
to switch on and off alternately as each pulse is 
dialled in. If it does not work, the flip-flop should be 
checked, especially for such things as the polarity 
of the diodes. When this is working, the second 
flip-flop should be connected to the first through 
the switch checking that this works. We should 
now be able to subtract and add up to two. The 
rest of the flip-flops are made, plugged in and 
wired to the switch in a similar fashion. It is 
important to check that when the switch is in one 
position all the inputs of the flip-flops are con- 
nected to the collectors of the preceding flip-flops 
corresponding to Tr2 and when it is in the other 
position all are connected to Trl (see Fig. 1). 

Conclusion 

The computer should function well. The phone 
dial gave a little trouble and the constructor is 
advised to be careful in the type which he buys. 
The wiring should be of thin single core type wire. 

The uses of this computer are mainly demonstra- 
tional and educational. It can be used as a counter 
of pulses, it being able to count up 2,000 pulses a 
second. However, when it is used as a counter of 
low repetition frequency pulses, a "squarer" has 
to be inserted before the input. ■ 



PRACTICAL ELECTRONICS = 

FEBRUARY ISSUE 

AUTO CALENDAR 
CAR BURGLAR ALARM 
DOORBELL REPEATER 

SPECIAL SERIES 

THE ELECTRONIC 0RGAN-3 



ON SALE JANUARY 13 - 2/6 

739 



RADIO 390 

& 

RADIO ESSEX 

Both fined £100 for 
illegal broadcasting 



390 sw itched -off pending 
appeal 

Essex (BBMS) carry-on 



ON Friday, 25th November, Nineteen Hundred 
and Sixty Six, Estuary Radio Ltd., who up to 
that time operated Radio 390 from a fort in 
the Thames Estuary, were fined the maximum of 
£100 at St. Augustine Magistrates' Court, Canter- 
bury, Kent, for unlawfully "using apparatus for 
wireless telegraphy, namely a transmitter without a 
licence, at Red Sands Tower on 16th August, 1966". 
Estuary Radio's managing director, Mr. Edward 
Allbeury. and company secretary, Mr. David Beres- 
ford Lye, were found guilty of the same offences, 
but were each given an absolute discharge. 



BROADCAST ON 773KC/S 

The Post Office had no difficulty in proving that 
Radio 390 had broadcast on approximately 773kc/s 
on 16th August, 1966, without a licence. Four Post 
Office engineers were called upon to give evidence: 
one to substantiate no licence had been allocated, 
and three to give evidence of monitoring the station 
and making tape recordings of the transmission — 
from Shoeburyness in Essex, Morden Point on the 
Isle of Sheppey and Heme Bay in Kent. 

UNDER BRITISH JURISDICTION 

Establishing whether the former anti-aircraft 
tower on Red Sands, from which Radio 390 
operates, came under British jurisdiction was an 
extremely complex matter. Sir Peter Rawlinson, 
Q.C., representing the defendants, told the court 
that Radio 390 is situated at least six nautical 
miles off the Kent coast and is thus well outside 
British territorial waters. John Newey, prosecuting 
for the Post Office, in this criminal case, did not 
agree and gave two main reasons to substantiate his 
claim. 

Firstly, under the terms of the Geneva Inter- 
national Convention of Sea, 1958, which was ratified 
in September 1964 by the British Government the 
Thames Estuary may be considered as a bay. But 
only if the amount of water (in area) within the bay 
exceeds that in a semi-circle drawn — with a 24- 



COLCHESTER* 



WALTON-ON-THE- 
NA2E 



I. FORELAND 




mile base-line — across the indentation in the coast. 
Lieutenant-Commander P. B. Beasley. head of 
Territorial Waters in the Hydrographic Department 
of the Ministry of Defence, told the court that in 
his capacity as a naval surveyor he had calculated 
the amount of water in the bay, with a base-line 
drawn across the indentation from Walton-on-the- 
Naze to North Foreland, and found that there are 
683 sq. miles in the 'bay' and five less in the semi- 
circle. His calculations, however, took in water in 
the Thames up to Greenwich and to Rochester 
Bridge in the Medway. Defence was not satisfied 
that this was permissible and laughter accompanied 
Sir Peter's suggestion of using Greenwich-on-Sea 
as a holiday attraction for a town situated in 
Greater London. 

The other factor, also based on the Geneva 
Convention, concerned low-tide elevations, which 
includes all islands that are un-covered at normal 
low water. Prosecution claimed that Middle Bank, 
one of the sandbanks off the Isle of Sheppey, is one 
and as such forms the inner limit of territorial 
waters. Although it is marked on Admiralty charts, 
Mr. V. Davis, master of the Mallard which has 
been supplying the forts for some time, stated that 
he had not seen Middle Sands uncovered for at least 
twelve months and is only uncovered after an ab- 
normal tide. 

CUSTOMS AND EXCISE 

Appearing upon a subpoena to give evidence 
for Radio 390, Mr. R. Stiff, a customs and excise 
officer based at Whitstable, Kent, told the court 
that his superiors had ordered the master of the 
supply ship Mallard to report before and after 
visiting the forts in the Thames Estuary. This order, 
he told the court, had been withdrawn in May 1966; 
under instructions from the Commissioners of 
Customs and Excise. He also told the court, under 
cross-examination, that no duty was levied on the 
transmitting equipment brought to Red Sands Tower 
from Rotterdam, and that the customs only require 
masters' to visit them and fill up a form when they 
are leaving for the high seas. 



740 



MARINE & BROADCASTING BILL 

Sir Peter Rawlinson, the former Solicitor-General, 
made reference to the Marine and Broadcasting 
Offences Bill, which has been introduced by the 
Goverment to suppress broadcasting from ships, 
aircraft and certain marine structures. It has not 
been through all the necessary stages to become an 
Act, he told the court, but it is a provision to deal 
with the problem you are faced with today. "If the 
present laws satisfy you that you have powers to 
deal with this case, what is the point of wasting the 
time of the Parliamentary draftsmen?'' 

Sir Peter explained that territorial waters could 
be extended by an Act of Parliament. However. 
The Territorial Waters Order in Council of 1964 had 
been made under the Queen's prerogative and is not 
an Act of Parliament. "If you accept that the Order 
in Council is not good law and is to be treated as if 
it were in the wastepaper basket, I suggest that you 
look at the International Convention which says the 
same thing." 

CHANGING THE BOUNDARIES 

Summing-up, Sir Peter Rawlinson said that it 
was a remarkable thing that this matter which 
affects the sovereignty of the realm should turn on 
the evidence of a distinguished officer (Lt.-Cdr. 
Beasley), but who only held the rank of a Lieutenant- 
Commander in the Royal Navy. He also made 
reference to the fact that no official map or chart 
indicated changes in territorial waters, concerning 
this case, and that under the terms of the Geneva 
Convention the general public must be informed 
of such changes. 

VERDICT 

After a second adjournment of thirty minutes 
(recall for further technical evidence from Lt.-Cdr. 
Beasley), Mr. Donald Andrews, Chairman of the 
Bench, read from a prepared statement: "We find 
that Red Sands is situated in territorial water. The 
Wireless Telegraphy Act of 1949 is silent on the 
question of local jurisdiction, but the territorial 
waters in question join the coast of Kent and for 
that reason we are of the opinion that the justices 
of the County of Kent have jurisdiction in this 
matter. On the evidence before us, we find the 
evidence proved." 

EQUIPMENT NOT CONFISCATED 

The Post Office made application to the court to 
confiscate the transmitting equipment, worth 
approximately £12,000, and for costs. John Newey, 
prosecuting for the Post Office told how easy it is to 
form a new company and start all over again. 

After a third retirement, the Bench passed sentence 
and refused the Post Office the right to confiscate 
the equipment, and their application for costs. 

NOT GIVEN UP 

Immediately after the case had been heard, the 
Mallard supply ship carried a pre-record tape to 
Red Sands, on which Mr. Allbeury gave the station's 
reasons for shut down and notice of appeal. "If we 
win the appeal", Mr. Allbeury told reporters, "we 
shall start broadcasting immediately. If it goes against 
us, we shall operate from another country on the 



Continent." He would not say which, but indicated 
the suggestion to be a last resort. 

Radio 390 was founded in September 1965 and 
was not a 'pop pirate', but broadcast — to quote Mr. 
Allbeury — "sweet music" for housewives. It had a 
claimed audience of four million and its profits 
were said to be in the region of £15,000 monthly. 



RADIO ESSEX 

On Wednesday, 30th November, just five days 
after the Radio 390 case, Mr. Roy Bates the owner 
and operator of Radio Essex was summoned under 
the Wireless Telegraphy Act of 1949 for using a 
transmitter without a licence at Knock John Tower 
in the Thames Estuary. He was also found guilty and 
fined a maximum of £100 at Rochford Magistrates' 
Court, Southend. 

Mr Bates, who now calls his station Radio BBMS 
(Britain's Better Music Station), appeared without 
council and pleaded that the court has no jurisdiction 
over the Knock John Tower, since it is more than 
three nautical miles off the coast of Essex. John 
Newey, prosecuting for the Post Office, followed 
the same lines as he used in the Radio 390 case 
over the Thames Estuary being a 'bay'. He also 
introduced low-tide elevations, claiming that West 
Barrow is one. This lies within three nautical miles 
of Knock John Tower and is marked as a low-tide 
elevation on Admiralty Charts. 

Mr. R. H. Dalton. Mr. J. F. Woods (Assistant 
Executive Engineers in the Post Office) and Mr. J. 
H. Ainley (an Executive Engineer in the Post Office) 
gave evidence of monitoring Radio Essex on 222 
metres and locating the station on 16th August 1966, 
from Heme Bay in Kent, Shoeburyness in Essex and 
Morden Point on the Isle of Sheppey respectively. 
The same three men gave evidence in the Radio 
390 case. Also as in the Radio 390 case, Mr. W. 
Goldsmith, a Higher Executive Officer in the Radio 
Service Department of the Post Office, stated that 
although application for a licence had been made, no 
licence had been issued. 

Mr. Bates did not cross-examine any of the 
witnesses and before the magistrate retired told the 
court "I do not wish to make any statement at all." 
He did, however, after the decision (and the Post 
Office's application to confiscate the equipment and 
for a portion of the costs), state that he wished to 
make an appeal against the decision and that the 
question of forfeiture should not be considered until 
after the appeal. The court made no order about 
costs or forfeiture. 

STILL ON THE AIR 

After the case was heard, Mr. Bates told Practical 
Wireless that he could not accept the jurisdiction of 
the court and that he planned to carry on broadcast- 
ing from Knock John Tower with his 25kW 
Medium Wave transmitter. 



APPEAL 

It is possible that during the interval 
between going to press and publication of this 
issue, one or both of these cases will come 
up before a higher court. Details will, of 
course, be published in a later issue. 



741 



THE 



MW 



COLUMN 



AS an experiment, we are going to run this column 
for the next few months, during the main MW 
DX season. 

Over the last few weeks conditions have been 
good for North America, with occasional West Coast 
openings — notably KING Seattle on 1090kc/s and 
KOMO Seattle lOOOkc/s. Best times for West Coast 
is from 0300-0700. As these notes are written, North 
America is going through a poorer patch, but the 
South Americans are more prominent and numerous. 

Asia has been quite good in the afternoons and 
late evening periods, examples being Voice of 
America, Hue (Vietnam), and Lucknow (India) both 
on 760 between 1600-1700, Kaifeng (China) on 930 
and Anwhei (China) on 940 (together with the 
Brazilian PRF4) around 2130. and Hanoi (North 
Vietnam) on 1010 at 2200. The best times to listen 
for Asia are 1330-1730 and 2030-2300 from October 
to March. 

One interesting aspect of MW DX is that you 
have the opportunity to hear countries you would 
not normally hear on short waves, such as Bermuda, 
Bahamas, Gibraltar, Greenland, Jamaica, British 
Honduras, Liberia, Surinam, Okinawa, and others. 

One word of warning to newcomers.. Identification 
of stations is generally more difficult (apart, of 
course, from Canadian, USA stations, etc.) since 
English is not usually employed at all. And since 
"openings" to certain areas and the reception of 
particular stations are far less consistent than on 
short waves, and are therefore far more important 
in a serious study of propagation, it is essential to 
be absolutely positive when claiming reception from 
a particular station. Should any doubt exist, it is 
important to state that the reception claim is 
tentative. 

As in all hobbies there are occasional black sheep. 
We get them in short-wave listening — the spasmodic 
appearance of a reporter who claims reception of 
difficult or virtually impossible stations. Such antics 
usually betray the "reporter'* but in MW work 
fictitious claims are much more readily apparent. 
Fictitious reporting is usually obvious to the 
experienced DX'er and the culprit is made unwel- 
come in clubs or asked to leave. Equally true is 
the fact that an innocent reporter making an improb- 
able claim may easily find himself viewed with 
suspicion. The answer is easy: make sure of the facts 
and if doubt exists add the word "tentative". 

Most MW DX enthusiasts use some form of loop, 
which has the great advantage of high directivity. 
Such a loop was described in the November issue of 
Practical Wireless, but readers without this issue 
may obtain details of my own loop on request. All 
I ask is for return postage to be included (or where 
applicable overseas, an IRC). 

Next month we will give details of recent station 
changes which have come to hand. In the meantime 
I would like to hear from readers interested in MW 
activity and in particular from Asia, the Pacific 
area or Latin America not only in stations heard 
but news of any important changes or new stations 

on the air. Alastair Woodland 

742 



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STEREO BALANCE 

How to use stereo balance control systems to 
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743 



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The impedance of this microphone enables you to use it 
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744 



PREAMP 




DYNAMIC 



A.S.ELLIS 



MICROPHONES 



WHEN using a dynamic microphone with a 
valve amplifier often it is necessary to con- 
vert the low impedance signal from the 
microphone into one suitable for feeding the' high 
impedance valve input circuit. This can be done 
with a transformer, but good microphone trans- 
formers are expensive. The device to be described, 
however, renders a microphone transformer 
unnecessary, provides extra amplification, and is 
both cheap to construct and compact in its con- 
struction. 

The circuit 

The basic circuit of the device is shown in Fig. 1, 
and consists of a single transistor in grounded-base 
configuration. A signal from a low-impedance 
source is applied to the emitter circuit via Cin and 
the amplified signal, at high impedance, is taken 
from the collector circuit via Cout. 

It is the configura- ■■ 

\ Cin 

\ | R - 

low > Ti-r 
/ %+ 

/ Vee 




Fig. 1: Simple impedance 
converter. 



tion's ability to func- 
tion as an impedance 
transformer which is 
of particular interest 
here: the low im- 
ped a n c e input is 
eminently suitable for 
dynamic microphones, 
whilst the high output 
impedance (in the 
region of a megohm) 
makes the circuit suitable for connection to the 
high impedance input circuitry of valve amplifiers. 
Additionally, the configuration is capable of devel- 
oping significant and useful power gain when so 
connected. Since, in the grounded case, the current 
gain is slightly less than unity, the configuration 
derives its power gain 
from the high voltage 
gain. For driving valve 
amplifiers, it is voltage 
gain which is particu- 
larly required, since 
valves are voltage- 
operated devices. 

The complete cir- 
cuit (see Fig. 2) is 
conventional, and re- 
quired little original 
thought on the author's Fig. 2: Circuit diagram of the 
part. The device complete unit. 




appears to have a fairly fiat a.f. response, and an 
additional point in its favour is its low battery 
consumption: about 600,uA from the 9-volt battery. 

The choice of Trl does not appear to be par- 
ticularly critical; an OC71 was used in the proto- 
type simply because it happened to be immediately 
available. Several different a.f. transistors have been 
tried in this circuit, all with equal success; a few 
r.f. types have also been tried, but on the whole, 
these tended to be noisier. Red spot surplus types 
are not recommended for the same reason. 

It is feasible that some improvement in quality 
would result if a low-noise transistor such as 
AC107 was to be used in this circuit. However, 
the expense involved would not necessarily be 
justified by the slight improvement so obtained. 

Construction 

The wiring shown is perfectly straightforward and 
should present no difficulties; details are given in 
Fig. 3. The transistor is wired into circuit last of 
all, and its leads must be covered with PVC sleev- 



** VToTrl 




*-ToSk2 
*-ToS1 (-9V) 



Fig. 3: Component layout on the paxolin board. 

ing. This is so that when the whole unit is finally 
assembled, the transistor may be bent across the 
tagboard without fear of causing short circuits. 
The case of the prototype unit was a discarded 
2 oz. tobacco tin measuring approximately 3| in. 
x 2\ in. x 1 in. This tin was found to be particularly 
suitable, although any available tin of comparable 
size may be used and drilled accordingly. The 
drilling details for the prototype are shown in 
Fig. 4. 



745 



3 /«" 



fa 



-h 



B N-fc 



« 



/ Hole sizes 
A=V 8 'dia 
B=6BA clearance b[ 1 '/j, 

r 



B-9—T 




^ Tr1 bent across t agboard 



Tagboard 




Shakeproof 
washer -~. 



DZB- 



- 6BA nut 
Tagboard 



Paxolin 
panel 



I-.: 1 - <■■■<'■ 



mrnn iii/mnmiiiaa 



,Tin 



Fig 4: (Top left) Drilling 
instructions for the case. 

Fig. 5: (Above and left) 

Dimensional data (a) and 

mounting details (b) of 

the paxolin panel. 

Fig. 6: (Top right) Layout 
of the finished unit. 



(b) 



• components list 



R3 1kQ 
R4 10ka 



C3 0-1 up 



Resistors: 

R1 470ft 
R2 33kO 
All 1 0%, £W carbon 

Capacitors: 

C1 8/tF, 1 5V electrolytic 
C2 25^tF, 1 5V electrolytic 

Transistor: 

Tr1 OC71 (see text) 

Miscellaneous: 

Two coaxial sockets; single-pole, single-throw 
switch; six-way miniature tagboard; paxolin panel 
measuring 1£ x 1i x 1/16 in.; 6 B.A. nuts, bolts and 
shakeproof washers; PP3 or equivalent battery; 
battery terminals; small piece of plastic foam; and a 
tin container (such as a tobacco tin) measuring 
approximately 3| x 2\ x 1 in. 




Piece of plastic foam wedged between 
battery plugs and tin, keeps battery in 
position 



Final assembly 

Layout of the major components within the case 
are shown in Fig. 6. The tagboard is mounted by 
means of a 6 B.A. nut, bolt and shakeproof washer. 
A piece of paxolin, the same size as the tagboard 
04- in. x H in.) is suitably drilled to receive the 
6 B.A. bolt, and is placed immediately between the 
tagboard and the tin so as to act as an insulator 
(see Fig. 5). It may be found that the centre- 
conductor of SKI requires shortening by about 
1/8 in. in order to prevent it fouling the tagboard. 

Once the tagboard has been secured within the 
tin, the final wiring details shown in Fig. 6 may 
be completed. Earthing connections to the tinplate 
casing are easily made by soldering direct. Finally, 
the transistor is bent across the tagboard (see Fig. 
6). Care is essential here to ensure that the leads 
are not bent too near the transistor envelope. 

Testing 

Having checked all wiring, and ensured that the 
battery polarity is correct, a low impedance micro- 
phone (between 50 and 200^) is connected to SKI 
via screened cable (coaxial type), and a similar 
connection is made from SK2 to the valve- 
amplifier high impedance input. For those new to 
the principles of amplifying microphone signals, a 
loud howling sound may result if the gain control 
is advanced too far, or if the microphone is too 
near the loudspeaker. This is known as acoustic 
feedback, and can be arrested by retarding the 
main amplifier gain control. However, this is not 
an altogether satisfactory solution, since to prevent 
feedback it may be necessary, in extreme cases, 
to turn the control to such a position that gain 
is so low as to be of little use. Alternatively, and 
if space is available, the microphone can be kept 
well away from the loudspeaker. This is the most 
generally used solution. The most reliable method 
of all is to employ a uni-directional microphone 
which will not pick up signals from the loud- 
speaker when directed away from it. This, how- 
ever, is a rather more costly solution. 

It will be found that long input leads to the unit 
will give no trouble, but since the output is at 
high impedance, the lead joining the unit to the 
main amplifier should be no longer than is abso- 
lutely necessary. Hum troubles may arise if this 
precaution is not taken. I 



746 



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EQUIPMENT 

All Items available as 
advertised. 



SINCLAIR TRANSISTOR AMPLIFIERS 

7.1't Amplifier 89/6; Z12 Power Pack 79/8; Stereo 25 Pre- 
Amplifier £9.19.6; Micro FM Radio Kits £5.19.6; Micro 6 
Radio Kit 59/6: Micro Amp. Kit 28/8 Post Paid. 



M 



MM 



= fe 



2-WAY RADIOS 

Super qnalitv. Brand new 
and guaranteed. 

s translator £8.15.0 pr. 

4 trnasistnr £7.19.6 pr. 

5 transistor £8.4.0 pr. 

6 transistor £9.19.6 pr. 
6 transistor De Luxe 

£17.10.0 pr. 

10 transistor £22.10.0 pr. 

13 transistor 300MW £31.10.0 ?r. 

13 Trans. 1W £85.0.0 pr. Post extra. 

These cannot In operated in t'.K. 

TRANSISTORISED 
TWO-WAY 
TELEPHONE 
INTERCOM. 

Operative over amazingly 
long distances. Separate 
call and press to talk 
buttons, 2-wire connec- 
tion. 1000's of applica- 
tions. Beautifully finished 
in ebony. Supplied com- 
plete with batteries and 
wall brackets. 
£6.10.0 pair. P. * P. 8/6. 




ZQMTRANSISTOR CHECKER 

It nan the full- 
est capacity for 
checking on A. 
B and I co. 
Equally adapt- 
able for check- 
ing diodes, etc. 
Spec . : A : 
0-7.0-9967, B: 
5-200. Ico: 0-50 
mlcroamps, 0-5 
inA. Resistance 
for diode 200Q— 1 ME( 
Supplied complete with instructions, 
battery and leads. £6.19.6. P. A P. 2 '6. 




P.C.R.1. RECEIVERS 

Brand Xew Condition— Fully Tested and 
Checked before despatch. 3 Waveband 
with RF Stage— Wonderful value. 
860-2080 metres 190-570 metres 5.6-18 
Me/s. with internal speaker £8.19.8. 
Carr. 10/6 with circuit. Plug in external 
power units. 230V A.C. 85/-, or 12V D.C. 
19/6. 



MAGNAV0X 363 TAPE DECKS 

Sew 3-flPeed I ape deck, supersedes old 
Collars studio deck. 2-track £10.10.0. 
4-track £13.10.0. Carr. Paid. 



AMERICAN TAPE 

First grade quality American tapes. 
Brand new. Discounts for quantities. 

3in.. 225i't. L.P. acetate 4/. 

3iin. 600ft. T. P. mylar 10/- 

oin., 600ft. std. plastic 8/6 

5in.. 900ft. L.P. acetate 10/- 

5in., 1,200ft. D.P. mvlar 15/. 

oin., 1,800ft. T.P. mylar 35/- 

ojin.. 1,200ft. L.P. acetate 12/6 

6jin.. 1,800ft. D.P. mylar 22/6 

5}in., 2.400H. T.P. mylar 45/- 

7In., 1,200ft. std. mylar 12/6 

7in., 1,800ft. L.P. acetate 15/- 

7in., 1 ,800ft . L.P. mylar 20/- 

7in., 2,400H D.P. mylar 25/- 

7in., 3,600ft. T.P. mylar 58/6 

Postage 2/-. Over £3 post paid. 

VARIABLE VOLTAGE 
TRANSFORMERS 

Brand Xew— fully Shrouded. Input 230v 
50/00 c/s. Output 0-260 
Volts. 

lAinp £4.10.0 

2.5 Amp £5.17.8 

5 Amp £9.0.0 

8 Amp £13.10.0 

10 Amp £17.0.0 

12 Amp .... £19.10.0 
20 Amp .... £32.10.0 
2.5 Amp Portable — 
Metal Case with Meter. 
Fuses, etc. £9.17.6. 

SILICON RECTIFIERS 

200v. PIV, 200mA B/6 

200v. PIV, 6 amp 6/8 

400v. PIV, 3 amp (SCR) 10/- 

400v. PIV. 3 amp 7/8 

1,000V. PIV, 650mA 6/6 

800v. PIV, 600mA 5/6 

800v. PIV. 5 amp 7/6 

400v. PIV. 500mA 3/6 

70v. PIV, 1 amp 3/8 

150v. PIV, 165mA | 1/. 

150v. PIV, 25 amp 19/9 

700v. PIV. 100 amp 49/8 

Discounts for quantities. Post extra 




TEST EQUIPMENT 

PORTABLE OSCILLOSCOPE CT-52 

A compact (9m. x Sin. x 16fln.) general purpose 'scope 
T/B 10c/s-40 kc/s. Baud width 1 Me/s. Mullard DG 7/5 
2jln. CRT. For operation on 200'250v. AX. Supplied 
complete with metal transit case, strap, test leads, and 
visor hood. Brand new, £22.10.0. Carr. 10/-. Supplied 
complete with lust met ions. 



OS/8B 





/U OSCILLOSCOPES 

High quality Portable 

American Oscilloscope, 3in. 
r.t. T/B 3o.'s-50ke;s X 
Amp: O-6O0 ke - Y 
Amp: 0.2 Mc/s. Power 
requirements 105-123v. 
AX. Supplied in brand 
new condition. Fully 
tested. £26. Carr. 10/-. 
Suitable 230-118 v. 
Tran.-fonner, 15/6. 



ERSKINE TYPE 13 DOUBLE 
BEAM OSCILLOSCOPE 

Time base 2 c/s-750 kc/s. Calibrators at 
100 kc/s and 1 Mc/s. Separate Yl and Y2 
amplifiers up to 5.5 Mc/s. Operation 
110/230 volt A.C. Supplied in perfect 
working order. .TOO 1 (1 fl 
Carriage 20/-. LM.IU.U 




TE-20 RF SIGNAL GENERATOR 

Accurate wide range signal 
generator covering 120 kc/s- 
S6OH1 - on 6 bands. Directly 
calibrated. Variable R.F. 
attenuator. Operation 200/ 
24"v. A.C. Brand new with 
Instructions. £1240.0. P. * 



LAFAYETTE TE-46 
RESISTANCE CAPA- 
CITY ANALYSER 

2 PF— 2,000 MFD, 2 ohms— 
200 Megohms. Also checks 
impedance, turns ratio 
insulation 200-250 v. A.C. 
Brand Xew £15. Car: 



P. 



S.A.E. for details. 



TE-900 20.000Q/VOLT 
GIANT MULTIMETER 

8m. full view meter. 8 Mfcnjl 
"calc. 0/2.5/10/250/l,000/5,OOOV 
A.C. 1/25/12.5/10/50/260/1.000/ 
5.000 V. D.C. 0/50[iA/l 10/100/ 
SOOmA/lOampD.C. L9K/SO0K 
20 Meg. Ohm. £12.19.6 P.P. 5/-. 




TE22 SINE SQUARE WAVE 
AUDIO GENERATORS 

Sine: 20 eps to 200 kc.'s. 011 4 bands. 
Square: 20 eps to 
30 kc/s. Output 
Impedance 5,000 
ohms. 200/250v. 
A.C. operation. 
Supplied Brand 
Sew and Guaran- 
teed with in- 
Btrnoilon manual 
and leads. £15 
Carr. 716. 




NOMBREX EQUIPMENT 

Transistorised Audio Generator 10-100,000 
c/s. Sine or square wave. £16.15.0. 
Transistorised Signal Generator 150 kc/s. 
350 Mc/s. £10.10.0. 

Transistorised resistance capacitv bridge 1 Q . 
lOOMegfl. lpF-l00jiF. £9.0.0. 
Transistorised induction bridge, !|iX-100H. 
£18. Mains operated Transistor power supply 
unit, output l-15v. np to 100mA. £6.10.0. 
All above post paid with batterv. 




CLEAR PLASTIC PANEL METERS 

l'ir-t grade quality, Moving Coil panel meters, available 
ex-stock. S.A.E. for Illustrated leaflet. Discounts foi 
quantity. Available as follows: Type SIR. 3SP, 1 21/32in. 
i fronts. 



1-0-lmA 

1mA . 

2mA . 

5mA . 

10mA 

50yA 32/8 20mA 

100|xA 29/8 50mA 

200jxA 27/6 100mA 

500|XA 25/- 150mA 

5Q-P-50HA 



100-0-100(iA 27/6 200mA ... 
50n-0-500p,A 22/6 800mA , . . 



22/6 
22/6 
22/6 



22/6 
22/6 



22/6 100V D.C. 

88/6 150V D.C. . 

22/8 300V D.C, 

22/8 500V D.C. 



22/11 
22/H 
22fti 

22/fi 



500mA 
750mA 

1AD.C 82/6 750V D.C. 

2AD.C 22/6 15VA.C. . 

5A D.C. ... 22/6 50V AX 22/8 

3V D.C 22/6 150V A.C. .... 28/8 

10VD.C. .. 22/8 300V A.C.... 22/6 

20V D.C. .. 82/8 500V AX. 82/6 

50V D.C. . . 28/6 'S - Meter 1mA 89/6 

POST EXTRA. Larger sizes available— send for lists. 



TE-51 NEW 

20.000n/VOLT 
MULTIMETER 

0/6/60 120 

l,2"oV. A.C. 

0/3/30/60/300 

800/3.000V. D.C. 

/ OOllA 1 12 / 300 

MA. D.C. 

n / OOK / 6 Meg.fl 

85/-. P. 4 P. 2/0. 





MODEL U50D MUL- 
TIMETER with meter 
protection. 20,000/ 
o.p.v. 0/.l/.5/5,'50/25Q/ 
IflOOV D.C. 0/2.5/10/ 
11 V D.C. 
0/.05/.5/5/50/250 mi, 

ohm. .0001 — .2 mfd 
—20— + 22 db. 
£5.19.6. P. ft P. 3/-. 




MODEL TE-12 

20,000 O.P.V. 0/.06/ 
0/30/120 .'600/1,200/ 
3.000/6,000v. D.C. 0/ 
6/30/120/600/1,200 v. 
AX. 0/60[iA/6/80/ 
600 mA. 0/6K/600K/6 
Meg./60 Meg.D.-P.F. 
—.2 MFD. £5.19.6. 
P. £ P. 3/6. 

MODEL 500. 30,000 
opv, 0/.5/l/2.5/10,"25 
/ 100 / 250 / 500 / 
1.000 v. D.C. 
/ 2.5 / 10 / 25 / 100 
/ 250 / 500 / l,000v. 
A.O. 

/ 50aA / 5 / 50 / 
500mAl 12 amp. 
D.C. 

/ 60K / 6 Meg. / 00 

Meg.O- £8.17.6. 

Post paid. 

CALLERS WELCOME I 

Open 9 a.m. to 8 p.m. every day Monday 
to Saturday. Trade supplied. 




(RADIO) LIMITED 

Phone: GERRARD 8204/9155 
Cables: SMITH EX LESQUARE 

3-34 LISLE STREET, LONDON, W.C.2 



747 



^^roacluray 



ELECTRONICS 



GARRARD 4 SPEED DECKS 
WITH CARTRIDGE: 

Autocliangers: AT6 Mk II £8.19.6. 
Autoslim £5.5.0. AT60 

£10.19.6. 3000, £8.8.0. 2000, 
£6.19.6. 1000. £5.19.6. ATS— 
Mono £6.10.0. P. & P. all changers 
7/6. 

SINGLE PLAYERS: 

SP25 with cartridge stereo or 
mono. £9.19.6. SRP 12, £4.5.0. 
P. & P. 7/6. 

CARTRIDGES: 

Stereo: EV26, 25/-. GP83, 15/-. 
Reuter. STD/2, 17/6. Mono: GC8, 
15/-. GC2. 15/-. Sonotone, 2T/SS, 
15/-. GP67, 15/-. P. & P. 1/-. 

MICROPHONES: 

Xtal Hand Mikes. 

BM3 and 200C. 30/-. P. & P. 2/-. 
Stand for same 9/6 & 12/6. P. & P. 
1/9. ACOS Mike 45. 21/-. ACOS 
Mike40. 18/6.Dvn. MikeDM-391, 
22/6. CM2 1 Xtal'. l2/6CM20Xtal. 
9/6. Magnetic Hm 63C with remote 
control switch, 15/-. Telephone 
Pick-up 10/6. P. & P. 1/-. Xtal 
Lapel Mike, 7/6. Guitar Mike, 
12/6. P. & P. 6d. 



BARGAINS IN 
TRANSISTORS: 

ACI27, AF114, 115, 116, 117. 
118. 1 19. OCI69, 170. 171, 172. 
200. 202, 203. 204. 5/6. 
OC72, 75. 82. 83, AAZ12,, 
BY38. BCZII.3 6. OC71. 81, 
3/-. R.F. Packs I OC44, 
2 OC45 8/6. AF Packs 1 
OC8ID. 2 OC81 CMullard). 
8/6. A.F. Pack 1 GETI 19. 5/6. 
GET113. RedSpot.2'-.OC26, 
28. 29. 9/6. ORP12 Light Cell, 
8/6. Diodes OA81. 2/3. OA91, 
O A95, 1 19. P. & P. on above 6d. 



TRANSISTOR 
ELECTROLYTICS: 

1, 2, 4. 5, 8, 10, 16, 25, 32, 
50, 100 mfd 15 volt working, 
1/3. P. & P. 6d. 
250 mfd DC 3/-. 500 mfd 12v 
DC, 3/-. 500 mfd 50v DC, 5/-. 
P. & P. 1/-. 



RESISTORS.* watt 10% from 
3.3 ohm to 10 meg 5d. each. 
4/- doz. P. & P. 6d. 



SPEAKER ENCLOSURES 
Tony Corner Cabinet 20 x 10 x 
7in. takes 10 x 6in. speaker 
covered in Rexine and Vynair, 
45/-. P. & P. 5,-. 

Blake cabinet size 18 x 24.? x 
9Sin.. fabric covered £4.10.0. 
P. & P. 10/-. 

Haydon, 161 x 15 x 71 in. fabric 
covered suitable for 12in. 
speaker, 45/-. P. & P. 7/6. 

Haydon enclosure fitted with 
12in. speaker and volume 
control, £4.17.6. P. & P. 10/-. 

Hi-Fi Bookshelf speaker en- 
closure foam lined, cabinet 
size I0£ x 5* x 7-lin. Teak 
finish. £3.0.0. P. & P. 3/6. 

Woofer for above £3.0.0. P. & 
P. 2/6. Tweeter 12/6. P. & P. 
1 /6. Condenser for crossover 
2/6. Terminals 2/6 pair. P. & P. 
6d. 

PLINTH Teak finish to match 
above Hi-Fi speaker size 
17J x 14 x 4in. for Garrard 
1000. 2000, 3000. AT60. SP25, 
£2.17.6. P. & P. 4/6. 

SPEAKERS: 

Elac Heavy duty Ceramic 
Magnets 11.000 line, lOin. 
round 10 x 6in. 3 ohm or 15 
ohm, 42/6. P. & P. 3/6. 8in. 
round 15 or 3 ohm. 38/6. P. & 
P. 3/6. E.M.I. 13i x8in. 15 or 
3 ohm, 42/6. P. & P. 3/6. 
E.M.I. Tweeter, 12/6. P. & P. 
1/6. R.T.C. 12in. 20 watt 15 
ohm. Ceramic magnet £5.5.0. 
P. & P. 3/6. 8 x 4in Elliptical 
30 ohm, 30/-. P. & P. 3/6. All 
other speakers supplied — 
Goodmans, Bakers. W.B., 
Wharfedale, Eagle. Tripletone. 



EARPIECES WITH CORD AND 

3.5 mm. plug. 8 ohm magnetic. 3/-. 
250 ohm, 4/-. 180 ohm with clip, 
6/6. Xtal 4/-. P. & P. 6d. 

TRANSISTOR SPEAKERS 8 ohm 
2in.. 8/6; 3in. 10/6; 3Jin. 12/6. 
P. & P. 1/-. 

PANEL LIGHTS, Neon 200-250v. 
2/6. 6v. Red. Blue. Green, Yellow, 
White (uses Lilliput bulbs) 3/- each. 
P. & P. 6d. 

PAPERCONDENSERSforCross- 
Over Units, 2 mfd. 2/6. P. & P. 6d. 



ROTARY SWITCHES 

2 pole Mains Switch. 3/-. 1 pole 
12 way, 2 pole 2 way. 3 pole 3 way. 

3 pole 4 way, 4 pole. 3 way, 3/6 
each. P. & P. 6d. 

PUSH BUTTON SWITCHES, 4 

button, 2 banks of 6 S.P.C.O., 
1 bank of 5 S.P.C.O. 1 off button. 
5/6. P. & P. 6d. 

BATTERY CHARGER TRANS- 
FORMERS AND RECTIFIERS 4 
amp. GEC Rect.. 15/-. Heavy 
Duty Transformer, 25/-. P. & P. 
3/6. 1 amp. Westinghouse contact 
cooled rect. . 7/6. Transformer 1 2/6. 
P. & P. 3/-. Large Croc. Clips, 2/6 
per pair, P. & P. 6d. 

FERROX ROD AERIAL with 
coils. 8 x 5 /i«in., 8 x fin. 5/6. 4 x Jin. 
4/6- P. & P. 9d. 



Stockists of • Eagle Products 

• Goodmans • W.B.» Wharfe- 
dale • Bakers • Tripletone 

• Linear, all makes of ampli- 
fiers and speakers supplied. 
S.A.E. please. Trade terms to 
bona fide dealers. 



92 MITCHAM ROAD, TOOTING BROADWAY, 

LONDON. S.W.17 Telephone BALham 3984 

(four minutes from Tooting Broadway Underground Station) 



VIKING STEREO 4 + 4 

HIGH QUALITY AMPLIFIER 




A high quality stereo amplifier, boilt to meet the requirements of budget HI-FI- 
Elegants! vied cabinet in black rexine and wood grained ends. Brushed aluminium 
panel, block and silver knobs. Quality components throughout. Ganged Bass 
and Treble control?, separate volume controls for each channel. Valves (Standard 
Model) 2 x ECL86 (De-Luxe Model) 1 x ECCS3 (2) x ECLS6. Output 3 ohms 
matching, suitable A.C. mains 230-240 volt. Cabinet size, 18Jln. wide, 5|ln. high, 
8jin. depth. Full instructions and guarantee. Send for leaflet. 
STANDARD MODEL (amplifier only). . . £11.11.0 plus 12/8 P. & P. and Ins. 

DE-LUXE MODEL (amplifier only) £18.18.0 plus I2.T. P. & P. and Ins. 

CABINET extra if required £1. 5.0 

CABINET separately £1.15.0 plus 7/ti P. A P. and Ins. 

VIKING 10-12. A twelve watt amplifier for use on 230-240 voll A.C. 
innlns. Inputs suitable Microphone, Record Player, Tuner, Tape Recorder, etc. 
Printed circuitry. Five Mullard valves, reliable components. Front panel contains 
2 Input Jacks, 2 Volume Controls, I Tone. Neon and On/Off switch. Designed 
to lit Into same type and size cabinet as Stereo. Fully guaranteed. Send for leaflet. 
Price (amplifier less case) £7.19.6 plus 12/6 P. & P. and Ins. 

VIKING X.P.15. A frustrated order offered at a fraction of cost (original 
price 39gns.), 15 watts output. Suitable for 210-240 Volt A.C. mains. Attractive 
Black Chassis with slotted Chromed steel top cover, size 15 x 7J x 7in. 4 Input 
Jacks. 2 volume controls, 2 tone. 5 Mullard valves. Fully guaranteed. Send for 
leaflet. 

Price Complete £12.19.6 plus 12/6 P. * P. and Ins. 

Famous VIKING P.A. BASS AMPLIFIERS. 15, 30. 40, 60 and 
100 Watts. Send for Uaflii. 

SPEAKER-ENCLOSURES — SPEAKERS — MICROPHONES — RECORD 
PLAYERS and TAPE DECKS. Send for leaflit*. 

Terms: C.W.O., C.O.D. Money back guarantee. 
VIKING (ELECTRONICS) LTD. I'toTeb^ dg E. 



Telephone: ELG3644 



LONDON N.W.10 



For quick, easy faultless soldering 




Easy to use and economical. Containing 5 
cores of non-corrosive flux, instantly 
cleaning heavily oxidised surfaces. No extra 
flux required. Ersin Multicore Savbit Alloy 
reduces wear of copper soldering iron bits. 



SIZE 5 

HANDY SOLDER 

DISPENSER 

Contains 12 ft of i 
coil 18s.w.g. 
Ersin Multicore 
Savbit Alloy. Quick I 
and easy to use. 
2/6 each 



SIZE 12 

Ideal for home 
constructors. 
Contains 102 ft. 
^.j of 18 s.w.g. Ersin 
'yjjff , Multicore Savbit 

S^' 1 r^efrn A n°y on a piastic 
SfcrW! 'eel. 15/- each 
SOrt-Sa (Also available 
in other sizes) 





NEW SIZE 15 

21 ft coil of 60/40 
Alloy, 22 s.w.g. in 
a dispenser. Ideal 
forsmall compon- 
ents, transistors, 
diodes, etc. 

3/- each 




BIB MODEL 3 
WIRE STRIPPER 
AND CUTTER 

Strips insulation 
without nicking 
the wire, cuts 
wire and splits 
plastic twin flex. 
4/- each 



From Electrical or Hardware shops. If unobtainable write to: 
MULTICORE SOLDERS LTD.. Hemel Hempstead. Herts. M29 B 



748 



the home 
workshop 

BY G J. THEASBY 



THIS article is intended for the beginner, who 
needs some idea of how to set out his space and 
equipment before actually beginning to build, and 
for the established amateur who feels that perhaps 
he isn't using the area at his disposal as well as 
he might, and yet does not quite know where to 
start. The actual layout is, in the end, dependent on 
the floor and wall space available, but the ideal is 
a room apart from the rest of the family, in the 
interests of peace and quiet, this also offers com- 
plete freedom from danger to the rest of the family 
and any visitors. If a separate room is not avail- 
able, then half a room, a shed in the garden, or a 



Further shelves 
and cupboards can 
be fitted here later 



Extension speaker 
with vol. control 



Oscilloscope 




Fig. 1: Suggested layout for the constructor. 

fold-out bench, built into the wall or an old 
cupboard. It should offer reasonable comfort all 
the year round, being neither too warm, too cold, 
or too damp. It all depends on what use the work- 
shop will get. An amateur using commercial equip- 
ment will need less space than one who is building 
his own, or seeking to improve existing equipment. 
This article assumes that the enthusiast will be 



doing some home building, and consequently deals 
with power, tools, equipment, light and space. 

Power 

Power may be broadly divided into three groups: 
(I) A.C. mains; (2) D.C., filtered and smoothed; and 
(3) Low voltage power, (9—12 volts). 

First A.C. mains, 15 amps should be enough for 
most workshops, but make sure the house wiring 
can stand the load. If the amateur decides to wire 
his own sockets and distribution board (see Figs. 1 
& 2), it should be tested by the local Electricity 
Board before being connected 
to the mains. Fit a fuse-box 
or contact breaker in a 
prominent position, wired so 
that it cuts power to all the 
workshop, so that in case of an 
accident anyone can shut off 
the power. (It is suggested at 
this point that the station is 
insured against fire, theft, or 
accident to visitors, and also 
damage caused by aerial col- 
lapse, etc.) Try to fit at least 
one mains outlet socket on the 
distribution board with an iso- 
lating transformer of adequate 
rating, suitably fused. All 
sockets, transformers and built- 
in equipment should be fitted 
with individual fuses, in addi- 
tion to the main cut-out. All 
equipment should be fitted with 
indicator lamps to show when 
they are switched on. Each 
socket and unit of mains- 
operated equipment should be 
efficiently earthed. NOT to a 
gas pipe, or to a water pipe, 
because many houses now have plastic water pipes, 
and this plastic will render the water-pipe earthing 
circuit useless. 

To obtain a good and reliable earth, obtain a 
length of motor car ignition cable, and bolt and 
solder the wire to a copper spike. This joint is then 
painted over with bituminous paint to prevent cor- 
rosion, and the spike buried in three to four feet of 



Further shelves 
and cupboards 
can befitted 
here later 



Distribution 
board for mains. 
For fuse box cut 
out position 
see text. 



5A 
15A 
13A 
2 pin 5A 
light bulb 
socket 



749 



damp soil. The wire is then taken into the work- 
shop in the normal way. It is best not to use the 
electricity mains earth at all, as it can be danger- 
ous. Instead connect all station equipment to this 
earth, except the receiver and transmitter, if any. 
Give this a separate earth as far as possible from 
the first earth, as the earth for a transmitter or 
receiver can form a part of the aerial system, and 
thus carry radio frequency power. 

A power unit supplying d.c. filtered and smoothed 
can be provided for equipment without a built-in 
power pack. Suggested ratings are 250-300 volts 
and 6-3 volts, at 200mA and 4 Amps respectively. 
All wiring should be kept neat and tidy. Mains 
wiring should be as far removed as possible from 
aerial and earth wires for minimum hum pickup, 
and test equipment leads should not be left dangl- 
ing, or one day you may be a test meter short! 
Wire should be of adequate current carrying capa- 
city, and run underneath shelves where possible. 

Lastly, low voltage supplies. These should be 
completely isolated from the mains, and be suitably 
fused. 



(1) A rriultirange testmeter. Here, ranges offered 
is a secondary consideration to the input resistance. 
No less than 20,000 ohms/volt for accurate readings: 
better still 50,000 or 100,000 ohms/volt. Best of all 
is an accurate valve voltmeter, with an input resist- 
ance of many megohms/volt. 

(2) A signal source. If possible a signal generator 
with outputs at a.f., r.f. and i.f/ frequencies. If not, 
a microphone for a.f., and an aerial for r.f. will 
suffice. 

(3) A signal tracer, which can be used in con- 
junction with the above for fault finding is a good 
(and cheap) piece of equipment. 

(4) A gramophone turntable, arm, and loud, 
quiet, fast and slow music records could be pro- 
vided for testing audio amplifiers. 

(5) Last, but by no means least, a soldering iron. 
The author uses a 25 watt instrument soldering iron 
costing 25s. and having interchangeable bits, and a 
replaceable element. In the author's opinion a 
"quick-heat" iron rated at about 250 watts is not a 
good bargain, especially when using it with transis- 
tors, and, of course the price is much higher. If a 
25 watt iron is thought too light as in the case of 



Tools 

Buy the best tools available; 
not only will they last longer 
and keep their edge longer, but 
will not slip or become loose 
fitting in their handles. Multiple 
screwdrivers are not to be 
recommended, as the quality is 
sacrificed for the novelty, and 
the separate blades are soon 
lost. A basic tool kit could be 
as follows: — one 8in. screw- 
driver iin. blade; one 4in. 
screwdriver iin. blade; one 



Aerial tuning unit Preselector Adjustable table lamp 



Aerial- 



Mains 
power 
sockets 



Aerial 

earthing 

switch 

Earth y 



neon screwdriver 500 volt rat- 
ing; three Phillips (crossed 
head) screwdrivers, small, 
medium and large tips; one pair 
insulated electricians' heavy 
duty pliers; one pair long nose 
pliers; one pair side cutters; 
one pair "Bib" wire strippers; 
one good pocket knife; one set 
B.A. spanners. These tools 
should have a rack made for 
them and should be returned to 
this rack immediately after use, 
to stop them rolling under 
equipment being used, tested or 
constructed. (See Fig. 1.) An 
excellent rack can be made 
from a strip of wood and some Terry clips. 




Fig. 2: Possible arrangement for the SWL or "Ham". 



Equipment 

Here again buy the best available. However in 
this section price alone is not a good guide to the 
equipment's quality. Buy a well-known make, and 
the quality will speak for itself. The actual equip- 
ment will depend on what the enthusiast decides to 
concentrate, so only a basic list is given. 



constructors making up their own chassis, then a 
65 watt iron will be large enough. 

The best position is with the fight on one side 
of the bench to avoid glare, especially with a win- 
dow. Lighting should not be fluorescent, as this, 
type of lighting can cause severe radio interference. 
The author considers that a light of the "Angle- 
poise" type is almost as good as the fluorescent 
light, as the fact that it will throw a shadow is 
offset by its "manouvrability". A window along 
the adjacent wall will give a good light during the. 



750 



day. and, perhaps more important, aerial and earth 
leads can be taken straight outside instead of trailing 
round the room to the window, picking up hum on 
the way. The proximity of a window will be very 
helpful when trying new aerials. 



Space 

The efficient use of space requires much thought, 
and as everyone's taste is different, again only a 
basic idea is presented. With today's miniature 
transistor equipment, it may be possible to operate 
a transceiver from a floor-standing ashtray, but 
most of us will need more space. Two suggested 
layouts are in Figs. 1, 2 and 3. Fig. 1 is for the 
home constructor, and Fig. 2 for the licensed ama- 
teur, or, without the transmitter, for the s.w.l. If 
commercial only gear is used, then the drawers and 
shelves can be left out, except those needed for 
books, etc, and the rig placed on a small table 
against the wall, with enough space for books and 
charts. 

If the bench is to be made from scratch, the best 
height will be determined by the chair with which 
it is intended to be used. The chair should be com- 
fortable without causing backache when used for 
considerable periods! The bench should be well 
made, as it will have to support a lot of weight, 
and a few shillings saved now may be pounds spent 
later when the bench collapses with costly equip- 
ment on it. The main point in most stations is the 
receiver, and this should be plac- 
ed so that it can be operated for 
long periods without eye or arm 
strain. To this end, the receiver 
tuning dial should be directly 
in front of the eyes, to avoid 
parallax error, and should 
be evenly lit, to avoid eye- 
strain. The tuning knobs should 
be about four inches from the 
bench, and operated with the 
elbow resting flat on the bench, 
this position being much less 
tiring than any other. To make 
the best of this the receiver 
should be about one to two 
feet back on the table. Space 
should be left for the log, 
microphone, key, etc., without 
being cramped. All dials and 
meters should be within reach 
while sitting at the bench, and 
all readable. To achieve this 
try to get the radio equipment 
in the right angle of the joint 
of two walls (see Fig. 3). The 
bench top should be covered with hard rubber to 
guard against shock, and should be jointless, to 
stop dust, bits of solder, and small bolts and screws 
being lost. 

Storage space is most important, and one soon 
accumulates parts such as nuts, bolts, springs, 
washers, resistors, coils, switches, etc., and a way 
must be found to keep them tidy. Small boxes can 



Shelf for A.T.U. 



bought, and stood on the floor or a table, or if the 
bench is home made, a number of shallow drawers 
(4in. — 6in.) should be constructed. This last method 
is the method used by the author, and if compart- 
ments are added to some drawers, then almost 
anything can be kept within reach. If the floor space 
is available, by all means expand outwards, but the 
only way for many amateurs is up, so make sure 
all shelving is really safe to carry what is placed on 
them. Oscilloscopes are cheap compared to the 
price of human life and limb! Keep the heavy 
stuff down near the floor, and put only the lighter 
equipment and boxes on the higher shelves. There 
is no point in wasting space by having deep shelves 
and then stacking only at the front, so make the 
shelves about 6in. wide, bearing in mind what is 
written above. Some wall space should be left free 
for charts, maps (great circle maps are best for 
"DX'ers"), and QSL cards. 

Surplus 

Spare components can be obtained very cheaply 
by cannibalising old receivers and ex-Government 
equipment. Chassis and old parts such as resistors 
and small capacitators can be re-used, but beware 
of re-using old electrolytics, these are best bought 
new. If a use can be found for 3-phase 400c/s 
motors, all the better, but the experience gained in 
dismantling old equipment is much more valuable, 
especially with regard to component layout. If 
receivers and other equipment are repaired, space 



Window 




be stacked on a shelf, a nest of component drawers 



Fig. 3: Layout for a "shack" in the house. 

should be left in the workshop for these also. Note 
to the beginners, now. Don't work on a live or even 
plugged in set, either with soldering iron or screw- 
driver, it can be dangerous to the extent of killing 
you! 

Secondly, don't be too miserly with cannibalised 
equipment, or the workshop will look more like a 
wholesalers than a place for one of the most inter- 
esting hobbies there is. ■ 



751 



I — ®— i 

preen ^-^ Redl 
I iMCMMj 1 



.T1 

LT44 



SINCE publication of the "Low Voltage Neon 
Indicator" article in the June, 1966 issue of 
Practical Wireless, several readers have 
enquired as to the feasibility of a more powerful 
push-pull transistor circuit whose output would be 
sufficient to drive a neon bulb. A further sug- 
gestion from one reader was that the device should 

cause a glow around 
vNeon both electrodes of the 

neon tube. One or two 
readers sent along their 
own suggestions for 
such a circuit and 
these were quite good, 
but unlike that sub- 
m i 1 1 e d here, used 
capacitive cross-coup- 
ling of the transistors, 
and were thus more 
expensive to build. 

The device consists 
of an inductance/ 
resistance tuned oscil- 
lator, whose circuit is 
shown in Fig. 1; no 
for tuning purposes, 
sometimes used for 




Fig. 1: Complete circuit of the 
push-pull neon driver. 



capacitors are necessary 
This type of oscillator 
"battery-to-mains" transistor inverters, for which 
purpose the components used have larger power- 
handling capacities than those specified in this 
article. 

The output waveform is a square-wave with 
plenty of overshoot as Fig. 2a depicts. Fig. 2b 
shows the waveform after it has been "clipped" 
by the firing of the neon. The small "pip" on the 
leading edge is due to the fact that the neon does 
not fire until a voltage is reached which is slightly 
higher than the steady burning voltage of the lamp. 

In comparison with the device described in the 
June issue, this push-pull neon driver is more 
powerful, and so consumes a lot more current; 
20 to 50 mA or more according to the load and 
other operating conditions. This is sufficient to light 



several neon indicators in parallel if series resistors 
are used, or one neon without a series-resistor will 
light up quite brilliantly, with illumination provided 
at both electrodes. By using the circuit of Fig. 3 
it is possible to light two neon tubes, each at one 
electrode. The peak voltage available from the 
oscillator when off load is over 150 volts; more 




§ +ve 

i? o — 



I 



tfcfl 



Firing 
voltage' 



Burning 
-voltage 



§ "*" 



Time- 



(b) 



BY100 ^~S 
s— v BY100 

Connect in place of neon 
bulb In fig 1 



Fig. 2a: Output wave- 
form showing clearly the 
overshoot on both peaks. 

Fig. 2b: The same wave- 
form after clipping. 

Fig. 3: Modification allow- 
ing the use of two neons. 



than adequate to fire most of the miniature neon 
bulbs which are available. 

As with the previous article, component layout 
is left to the ingenuity of the reader, and should 
present few problems. Due to the simplicity of the 
circuit, the small size of the components, and the 
fact that the layout is not critical, the neon driver 
may be built into quite a small space. ■ 



RECEIVING THE BBC STEREO PROGRAMMES 



For some inexplicable reason, the grid of the 
triode of the circuit in Fig. 7 and the collector of 
Tr4 in Fig. 8 (article of the above title, December, 
1966 issue, page 857) are labelled respectively 
"from collector of Tr4" and "to triode grid of ECF80". 

These markings are, of course, incorrect, and the 
corresponding points relate to suitable connections 



for a stereo indicator, which in the article are 
referred to as points "A". 

While the error will be obvious to most readers, 
some may be confused and think that, perhaps, the 
"valve circuit must be partnered with the transistor 
circuit. This, of course, is not true as the two circuits 
are entirely separate. — K. Royal. 



752 




s 



for 144 Me/s 



IN a super-regenerative receiver regeneration is 
advanced far beyond the point where oscilla- 
tion commences, but is interrupted at a 
frequency above audibility. This provides very high 
sensitivity. The super-regenerative receiver described 
here uses easily obtainable valves, and tunes 
approximately 142-150 Mc/s with the coils 
employed. Coverage can readily be modified by 
altering the coils. 

A 954 acorn valve is used for r.f. amplification, 
and to help isolate the oscillating stage from the 
aerial. Output is coupled to L4 by L3. V2 is the 
detector. Grid rectification causes a negative grid 
potential which stops oscillation until the charge has 
leaked away through R3, when oscillation recom- 
mences. The values of R3 and C4 allow this to 
happen at above audible frequency. 

VRI adjusts regeneration by varying the h.t. volt- 
age applied to V2. In a super-regenerative detector 
a loud hiss is heard when no signal is present, but 
this almost ceases when a signal is tuned in. V3 
is an audio amplifier, and V4 the output stage. 

For smooth regeneration and lack of various 
feedback effects, a separately decoupled h.t. supply 
was found necessary for VI and V2. This is prefer- 




F.G.RAYER G30GR 



ably obtained from a voltage regulator, but satis- 
factory results are possible by voltage dropping 
from the 250V line as shown in Fig. 6. 

Chassis layout 

The prototype chassis was 6 x 6 x 3 in. deep. The 
panel is supported by large brackets, and these also 
brace the vertical screen carrying VI, V2 and VC2 
(see Fig. 2). This provides a front section with VI 
grid and other circuits, while VI anode and V2 
holder tags are behind. The audio stages V3 and 
V4 are on the chassis. 

The vertical screen can be largely wired in 
advance. Punch holes for VC2, V2 holder, and a 
clearance hole for VI (Figs. 3 and 4). The con- 
nections in Fig. 3 are when viewing the acorn valve 
from its shorter or grid end (also see Fig. 2). Care 
must be taken when soldering, or the valve seal 
will be broken by heat. Leads are shaped and cut 
so that there will be no strain on the valve pins, 
and they are tinned with solder. CI and C2 have 




Fig. 7: Circuit diagram of the receiver section. 




753 



Aerial 



C^R4 




ifpie 



pan 



Fig. 2: Top view of chassis layout. Note the positioning of 

the components. At these high frequencies the shortest 

possible leads should be used. 

the shortest possible wires. Clean the valve pins, 
if necessary, and tin the extreme ends with cored 
solder and a hot iron, which is removed imme- 
diately the solder flows. The valve is then soldered 
in as in Fig. 3, with equal care. 

Fig. 4 shows the rear of the screen, leads to 
V2 and the items in the tuned circuit are kept as 
short as possible. Fit soldering tags so that tags 4 
and 7 of V2 holder may be soldered to them with- 
out wire, (Fig. 2). Tag 1 goes to VC2 at its nearest 
point (Fig. 2). 

Capacitor modification 

VC2 has four moving plates, and two fixed 
plates, isolated from each other. It was made from 
a 75pF short wave variable capacitor. The spindle 
retaining clip was pulled out with a pointed tool, 
and the spindle and moving plates withdrawn. 
Unwanted plates were removed from the spindle 
by bending them from side to side with small flat 
nosed pliers. If the capacitor has plates assembled 
on threaded rods, with spacers, it should be taken 
apart to remove the plates. The rotor had nine 
moving plates. Counting from the back, leave 
plates 1, 3, 6 and 8, and remove the others. Remove 
all the fixed plates one at a time, and note that 
the capacitor is not a type with the two fixed plates 
supports joined by a metal strip in front. Replace 
the spindle. Prepare two fixed plates by cutting off 
one lug of each. Put one such plate between the 
front pair of moving plates, and solder it to one 
support. Put the other plate between the rear mov- 
ing plates, and solder it to the other support. Each 
section of VC2 is thus a single fixed plate between 
two moving plates, double spaced. The capacity 
is approximately 5pF each section. 

The screen is bolted as in Fig. 2. A coupling 
and piece of \ in. rod couples VC2 to the ball 



754 




drive, which occujfies a hole in the , 

latter was varnishe|d hardboard backed by aJ 

ium sheet. VC1 has.no reduction drive. ^^^^ 

Details of winding the coils are as follows: 
LI; 2 turns of 18 or 20 s.w.g. insulated wire, and 
placed between the turns of L2. L2; 4i turns of 
16 s.w.g. enamelled or bare wire, spaced to | in. 
long. L3; 2 turns of insulated wire at the centre 
of L4. L4; 5 turns of 16 s.w.g. wire spaced % in. 
long. All coils are 7/16 in. outside diameter. 

To make L2 and L4, straighten the wire and 
wind turns side by side on a suitable object. Run 
a small tool round and round between turns, or 
stretch the coil to the required length. Shape and 
cut the ends and solder them to the appropriate 
points. LI and L3 are made in the same way and 
fitted as in Fig. 2. 

RFC1 is 70 turns of 34 s.w.g. enamelled wire, 
close wound on a 5/16 in. diameter ^former. It was 
a push fit on a bolt attached to the .Trtical screen. 
Adhesive is applied to the ends of the winding 
only. 

RFC2 is wound on a 2\ in. piece of i in. 
diameter insulated rod. Secure 34 s.w.g. enamelled 
wire near the top. Wind 70 turns side by side and 
again secure with adhesive or tape. Bind the 
extreme bottom of the rod with a few turns of 
bare wire, and solder on a tag bent at right angles. 
This tag is bolted to the chassis, and is an earthing 
point for C5 (Fig. 2). Solder the top choke lead 
to the centre of L4. Other v.h.f. type chokes should 
be satisfactory. 

Audio amplifier 

The audio and output stages are wired as in Fig. 
5. Any slight leakage in C7 or C9 will upset the 
audio stage grid voltages, therefor these capacitors 
should be tested if not new. A tag strip anchors 
the two h.t. positive supply leads. Insulated leads 
for power supplies and speaker pass through a 




6-3V 



Fig. 3 (above): Top chassis screen viewed from the front. 
Fig. 4 (below): Top chassis screen viewed from the rear. 




hole in the chassis. If the speaker transformer is 
Separate, and not attached to the speaker, the 
Htnsformer could be bolted to the chassis under- 
neath, near V4. When using a speaker with trans- 
^>rmer attached, remember that the h.t. voltage is 
present on connections from receiver to transformer 
primary. 

Current can probably be taken from an existing 
power pack. The heaters require 0-9 A at 6-3 V. The 
audio stages draw approximately 60mA at 250V. 
Current required at the 130- 150V point is small, 
depending on the setting of VR1, and averages 
about 4 — 6mA. 

Power supply 

A suitable power supply circuit is shown in Fig. 
6, and can be modified in some cases to suit items 
to hand. The 6*3V winding may be rated at more 
than 1A. If this winding can supply 2A or more, 



.H.T.+13C/l50V JHT.+ 250V 




Fig. 5 (above): Under chassis wiring of the receiver. 
Fig. 6 (below): Circuit of a suitable power supply. 



r^sm^ 



R9. 
6-2kn« 

3w; 



+ 130/150V 



?K 



5V2A<^ 



V5 
5Y3 



C13 C14 I s S\ 

16jjF 8mF. \ 



8BT1* 

:kn 



Common 



x_ 



3W 



250< 
V < 



80 o 

mA 



250VO 



6-3V lAo) 



S1 



8 



A.C. 

mains 

(o O 




• components list 



Capacitors: 

C1 2000pF 1 50V disc ceramic 

C2 2000pF 1 50V disc ceramic 

C3 2000pF 250V disc ceramic 

C4 50pF mica 

C5 2000pF 250V disc ceramic 

C6 0-25/xF 250V paper tubular 

C7 001 /xF ceramic or mica 

C8 25/xF 1 2V or similar electrolytic 

C9 0-01 /aF ceramic or mica 

C1 25/i.F 25V or similar electrolytic 

C11 001 mF 350V 

C1 2 8^F 350V electrolytic 

C1 3 1 6/tF 350V electrolytic 

C14 8/iF 350V electrolytic 

VC1 15pF variable 

VC2 5 +5pF variable (see text) 

TC1 30pF air spaced concentric trimmer 

VR1 50kQ linear pot. 

VR2 500kO log pot. 

Resistors: 

R1 100kHiW R6 100kO£W 

R2 1-2kfliW R7 470kDiW 

R3 8-2MfiiW R8 270fi 1W 

R4 33kiiiW R9 6-2kQ 3W 

R5 2-2kOiW R10 10kQ3watt 

Valves: 

V1 954 acorn V4 6BW6 

V2 6C4 V5 5Y3 

V3 6C4 

Miscellaneous: 

Two B7G holders. One B7G screen, B9A holder, 
LI, L2, L3 and L4, RFC1 and RFC2, see text, Ball 
drive, Co-axial socket, 10H 80mA choke, Mains 
transformer 250-0-250 at 80mA, 5V at 2A, 63V at 
1 A, Switch 1 pole 2 way, 4-sided chassis 6 x 6 x 3in., 
6 x 3in. flanged runner (Home Radio), 6 x 6in. panel. 
Two panel brackets about 5 x 5in., Knobs, tag strip, etc. 



and there is no 5V winding, a 6-3V rectifier such 
as the EZ81 can be used, in which case the recti- 
fier cathode is taken to the h.t. smoothing choke 
only, and all heaters are then in parallel. 

H.T. drain can be kept down to a suitable level 
for a 60mA transformer by using 12kH and 20kfl 
resistors instead of 6-2kil and lOkfi, and by 
increasing R8 to 330O. Smoothing capacitors need 
not be the values shown, and can be 350V or 450V. 
The choke is any small 60mA or 80mA smooth- 
ing type. The power supply is built on a separate 
chassis, size to suit individual components. 



Receiver adjustment 

With L4 wound as described, TCI is almost 
completely open for the 144Mc/s. band. A very 
small adjustment of TCI has considerable influence 
on waveband coverage. Later, it can be rotated 

— continued on page 773 

755 




OE SIGNAL 



95 KC/S — 85 M C/S 



THIS generator is suitable for receiver 
calibration and alignment, and for quick 
stage-by-stage checks of r.f., i.f. and audio 
circuits. Unmodulated (c.w.) or modulated r.f. out- 
put is available on fundamentals through all 
frequencies from lOOkc/s to 80Mc/s, and harmonics 
may be used up to 160Mc/s. 

Figure 1 shows the circuit, which is for a.c. 
mains operation. The 6-way switch SI A and SIB 
selects any of six coils (LI to L6) which are tuned 
by VC1. The coverage obtained by the author was 
as follows, but the extreme ends of each band are 
unused: Band 1, 95-360kc/s; Band 2, 280-1050 
kc/s; Band 3, 890kc/s-3-3Mc/s; Band 4, 2-4- 
10-5Mc/s; Band 5, 7-25-36Mc/s; and Band 6, 30- 
85Mc/s. All ranges are with the full 180-degrees 
rotation of VC1, except for Band 6, which is cov- 
ered by approximately half-capacity (90-degrees 
rotation). All the coils are of fixed inductance, to 
avoid possible loss of calibration. 

One triode section of the 12AU7 acts as r.f. oscil- 
lator, with output from the cathode via C3 to the 
6BA6 amplifier and mixer. The remaining triode 
section functions as an audio oscillator, with injec- 
tion to the 6BA6 suppressor grid; VR1 allows con- 
trol of the output. The 3-way switch S2A and S2B 
provides oscillator switching. 

A small convertor type mains transformer sup- 
plies h.t., the drain being about 20mA at 165V. 
The two heaters need 6-3V, 0-6A. The h.t. line 
voltage is not too important, but oscillation may 
cease on Range 6 if this is much under 160V. 



Case 

A neat, strong and inexpensive aluminium case 
was made by the author from "Universal Chassis" 
members; using two 10 in. x 3 in. runners, two 
8 in. x 3 in. runners and two 10 in. x 8 in. plates. 
Assembled, these provide a cabinet measuring 
10 in. x 8 in. x 3 in. A further 10 in. x 3 in. runner 
acts as chassis. 

A different cabinet or case already to hand could 
probably be used and the layout is not likely to 
prove critical except for the r.f. oscillator. 

The 10 in x 3 in. runner has its corners cut so 
that the case sides will fit (Figs. 2 and 3) and 
it is bolted to the panel so that its surface is 2} in. 
from the lower edge. The valveholders and mains 
transformer are fixed as in Fig. 2. VC1 is attached 
to the panel with three countersunk bolts; spacers 
being placed between panel and capacitor. A well 
insulated lead is soldered to the lower fixed plates 
tag before mounting the capacitor, and this passes 
directly through a hole in the chassis. A short lead 
also connects the rotor contact tag to another 
bolted to the chassis. Nearly all wiring is done 
before fixing the case sides. 

Under the chassis 

Wiring and components are shown in Fig. 3. 
Place the bandswitch so that the shortest possible 
leads may be used from SI A to Rl, CI, and tag 
7 of the valveholder. Leads to C2 should be very 
short, and also from tag 8 (cathode) to SIB. 



Only one coll shown 

R1 
47kfl 
5q 6 Q / r-VVWV-, 



S1A 



VC1 / 
500-5 

pF 7 

>U-LG 



C1 
100pF 



MCW, 



I 



^12AU7 



° S1B| 
2o 



S2A 



.R3 

•22k.n 

i1W 



R5- 

22kn: 



-\MAV 
R7 
ikfi. 



•R8 
:3900. 



CZl::' 



cilh 

20pF 



R2- 

iook.n: 



R4J 
47kO.< 



C2 

2000pF 



Tf 



C9 
O-OlpF 



fFs2B i ^4 

■-o-*-? CIO C11 A i. 



XC6 



O'OljjF 



3 "4 
6BA6 




C10 C11 
16pF BpF 



C4 ' 

10OOpF 
1kV 



VR1 
50k O. 



R6 

• 2-2M0 



L Rectifier 



A.C. 

mains 



220V _ 
20mA ci 



6-3V 0-6A 



Heaters 



rc 



o S3 



N 

E 

£3 



756 





R. F. GRAHAM 



Heater and h.t. lines can run against the chassis. 
A tag strip was used as anchor points for C7 and 
the leads from L7. All wiring should be rigid, the 
coils being left until last. 

The function switch can be wired from Fig. 4. 
Section S2A applies h.t. to the r.f. oscillator in both 
"CW" and "MOD" positions. Section S2B supplies 
the audio oscillator with h.t. in both "MOD" and 
"AF" positions. 

Audio choke 

L7 is an audio choke, the capacitors C6 and C7 
providing an effective centre-tap. A small transistor 
receiver output coupling transformer was used by 
the author, whilst almost any transistor driver 
transformer or other small audio choke or trans- 
former could be employed. The winding carries 
no direct current. 

If the component has more than one winding, 
each winding can be tried separately, or both can 
be used in series, reversing connections to one if 
necessary. This, allows the tone produced to be 
modified. It is also possible to lower the pitch by 
increasing the values of C6 and CI, or raise it by 
reducing these values. When first testing the gener- 
ator, it is best to listen to the audio output with 
headphones. 

Coils 

In view of the large number of turns, ready- 
made coils were used for Bands 1 and 2. The coils 
for Bands 3 to 6 were home wound. Each coil 
has a single winding (or easily-arranged equivalent) 
with A going to SI A, tapping B to SIB, and the 
end to chassis (see Fig. 5). 




As it is difficult to tap small ready-made coils, 
extra turns were added for Bands 1 and 2. These 
extra turns can be looked on as a continuation of 
the main winding, and are in the same direction. 
Therefore the earth end of the original winding is 
now joined to the beginning of the extra coil, and 
forms the cathode tap B. The end of the new wind- 
ing C goes to chassis. 

Band 1 (100-350kc/s) This was a surplus long 
wave aerial type coil, with 6 turns added to pro- 
vide a tapping, as already described. A piece of 
ferrite rod 3/8 in. in diameter and 1| in. long 
was pushed into the coil and cemented. Another 
coil was also found suitable, with tuned and coup- 
ling windings connected in series to increase the 
inductance. An unmodified l.w. coil can be 
expected to give coverage to about 1 50kc/s. 

Band 2 (300-l,000kc/s) This was also an old long 
wave aerial coil with the coupling winding and core 
removed, and some turns unwound until suitable 
coverage was obtained. Five turns are re-wound to 
give a tapping five turns from earth. 

Band 3 (Calibrated 0-9Mc/s to 3-3Mc/s) This is 
74 turns of 32 s.w.g. d.s.c. wire, found in a compact 
pile on a |in. diameter former (Fig. 3); tapping B 
is six turns from C. 

Band 4 (2-5-1 OMc/s) This coil has 50 turns of 32 
s.w.g. enamelled wire, side by side on a i in. 
diameter former, with tapping B two turns from C 

Band 5 (7-5-34Mc/s) This is also on a \ in. former, 
and has seven turns of 24 s.w.g. enamelled wire 
side by side, with tapping B one turn from C. 

Band 6 (32-80Mc/s) This is 3| turns of 16 s.w.g. 
wire 7 in. outside diameter and f in. long. End A 



Fig. 1: (Left) Complete circuit 

diagram of the wide range 

signal generator. 



Fig. 2: (Right) Top view of the 
chassis. 



Mains transformer T1 



Note:— 
lags marked M.C 
denote earthing 
points to chassis 





To rectifier 



757 



is iin. long and end C is |in. long, soldered directly 
to switch and a tag bolted to the chassis (Fig. 5); 
tapping B is U turns from C. 

All the coils, except that for Band 1, are air- 
cored. Various ready-made coils are likely to be 
satisfactory. If those with cores are employed, it 
makes it easier to obtain correct coverage, but the 
cores must be sealed before calibrating the gener- 
ator. 

Bandswitching 

Connections are shown in Figs. 3 and 4. Leads 
to the Band 5 coil should be as short as possible. 
For Band 6, the coil is placed and connected as 
shown in Fig. 5. The switch has two wafers, and 
should be connected as in Fig. 4 so that the 
shortest possible circuit is obtained for Band 6. 

It was found that with a smaller coil for Band 6, 
giving coverage up to lOOMc/s, r.f. oscillation 
tended to cease towards the top end. Oscillation was 
maintained up to over 85Mc/s with the coil shown 
and thus the second harmonic allows output up 
to 170Mc/s. 

Each coil is electrically separate from the others, 
so can be checked or modified individually, if 
necessary. No changes should be made after cali- 
bration, of course, and the whole instrument 
should be kept in its case. 

Scales and cursor 

A semicircular scale of thin white card (7| in. in 
diameter) cemented to the panel was used by the 
author. The cursor was cut from perspex and fixed 
to a large knob by three self-tapping screws. A 
hair-line was scribed along the underside of the 
cursor and six equally-spaced 1/1 6th in. holes 
drilled on this line, so that calibration marks could 
be made by placing a pencil point in them. 

The knob, with cursor, is locked to the capacitor 
spindle. The six semicircles can then be drawn by 
(placing a pencil or "Uno" type pen in the appro- 
priate holes. Mark with dots maximum and mini- 
mum settings on the outer scale, so that the cursor 
can be replaced correctly if removed. 

The holes were also found very helpful when 
calibrating the generator. Markings were made in 




pencil, then in ink after a final check. With care, 
the accuracy should be at least equal to that of 
the popular type of "off-the-shelf" generator. There 
are several methods of providing calibr ation 
depending on the equipment to hand. 

Use of harmonics 

Calibration of the generator (or a receiver 
be aided by employing generator harm 
multiples of frequency. If a receiver is tuned to 
the long wave Light Programme, this is 200kc/s. 
With the switch at CW, tune the generator until 
its output heterodynes with the Light Progamme 
signal. This is easily done by using Range 1, 
closing VCI from minimum position. The hetero- 
dyne whistle on the receiver falls in pitch towards 
the correct generator tuning point, rising again as 
this point is passed. This will also happen with 
harmonics. The receiver merely compares the 
generator and Light Progamme (or other frequency 
standard) sienals. The generator can thus be cali- 
brated at 200kc/s. Further rotation of VCI will 
produce a similar heterodyne. This is lOOkc/s 
(VCI nearly closed) and can be marked. 

With the generator returned to 200kc/s (zero 
beat with Light Programme) its output can be 
tuned in on the receiver at multiples. That is, 400, 
600, 800kc/s, and so on. If the generator is tuned 
to lOOkc/s as described, its harmonics appear at 
200, 300, 400, 500, 600, 700kc/s, and so on. This 
allows accurate calibration of a receiver at lOOkc/s 
points. 

By tuning the generator to 200kc/s (zero beat 
with Light Programme) lMc/s can be found accur- 
ately on the receiver (5th harmonic, 300 metres on 
medium waves). If receiver tuning is then left 
untouched, the generator can be tuned to lMc/s 
in Ranges 2 and 3. This can be marked. So can 
generator frequencies providing harmonics on 
lMc/s. That is, 500kc/s, 250kc/s and 125 kc/s. The 
receiver can also be tuned to harmonics lMc/s, 
allowing calibration at 2, 3, 4, 5, 6Mc/s, and so on. 

When proceeding in this way, an all-wave 
receiver with a large dial is very useful. A t.r.f. 
receiver with regeneration just sufficiently advanced 
to cause a heterodyne is perfectly satisfactory. A 
superhet should have some form of tuning indi- 
cator, or a b.f.o. 




Taps 




Coils 1 and 2 
A B 



Coil 3 



C2S\ 

L7 C6 R3.R4 CIO 

Fig. 4: S1A & S1B switch connections. 

To avoid errors, calibrate the generator by beat- 
ing its output (at a harmonic, if necessary) with 
a known signal. Working from 200kc/s as des- 
cribed will locate 2-5Mc/s so that M.S.F. on this 
frequency can be heard (most of the transmission 
is one second pulses). This allows 2-5Mc/s to be 
confirmed on the generator, and with its tuning 
untouched allows, 5 7-5, lOMc/s and other har- 
monics to be found on the receiver with great 
accuracy. 



Crystal marker 



A lOOkc/s or lMc/s crystal marker is used by 
many short wave enthusiasts, and permits quick 
calibration. Adjust the receiver to marker pips in 
turn, tune the generator, and mark its scale. By 
beating generator harmonics with marker har- 
monics, the scale can be sub-divided as necessary. 
For example, 50kc/s markings may be found with 



• components li 



C7 001 /.F 
C8 001 ,iF 
C9 001 ,tF 
C10/C11 16/8/xF or 
similar 350V electrolytic 



Resistors: (J- watt except where stated) 

R1 47kQ R5 22kQ 

R2 100kO R6 2-2MQ 

R3 22kO(1-watt) R7 1kQ 

R4 47k£2 R8 390ft 
VR1 50kO potentiometer 

Capacitors: 

C1 100pF 

C2 2000pF 

C3 20pF 

C4 1000pF, 1kV 

C5 1000pF 

C6 001 ^F 

VC1 500pF air spaced 

Switches: 

S1 A/S1 B 2-wafer, 2-pole 6-way 
S2A/S2B 2-pole 3-way 

Valves: 

12AU7 (or ECC82) and 6BA6 

Miscellaneous: 

L1-L7 as described, B9A holder, B7G holder, 
coaxial socket, mains on/off switch, 250V 25mA 
contact cooled or similar rectifier (5-wave), mains 
transformer (220V 20mA HT J-wave, 6-3V 0-6A), 
Universal Chassis box 10x8x3 in., 10 x 8 in. 
back plate, 10 x 3 in. extra runner, mains cord, tag 
Strip, etc. 




Coils 4 and 5 
A bS, 




To S1B Fig 5 . Coi i d eta ji s 
for L 1 to L6. 



T3T 



a lOOkc/s crystal if the receiver is tuned to the 
generator's 2nd harmonic. Then 150kc/s on the 
generator is 300kc/s on the receiver, while 250 
kc/s on the generator is 300kc/s on the receiver, 
while 250kc/s on the generator is 500 kc/s on the 
receiver, and so on, the lOOkc/s multiples being 
from the crystal. 

To avoid counting off lOOkc/s intervals over high 
frequency bands if a lMc/s crystal is not available, 
the lMc/s point can be found from the lOOkc/s 
crystal, then used to mark lMc/s points, later 
confirmed if necessary with the lOOkc/s harmonics. 

Accuracy 

Any equipment should be switched on for 20 
minutes or so, before using it to calibrate the 
generator, which should have also thoroughly 
warmed up. As the calibration procedure only has 
to be done once, care should be exercised. There 
is usually no need to rely on visual re-setting of 
the receiver or generator, during calibration, 
because settings are found by heterodyning the 
signal or its harmonics. 

Wavemeter or G.D.O. 

Various surplus and other wavemeters of good 
accuracy are available. If one is to hand, and 
has a milliammeter indicator, it can be used by 
coupling it as loosely as possible to the generator 
coil. This gives a quick method of calibrating the 
scales lightly in pencil, as a useful guide to sub- 
sequent more accurate calibration as previously 
described. 

A grid dip oscillator can be used in the same 
way, the signal generator being switched off. 
Couple the g.d.o. lightly to the appropriate coil. 
If this is done carefully, with an accurate g.d.o., 
results will agree very nearly with final calibration, 
and are thus a useful guide to avoid counting 
harmonics. 

Calibrated generator 

If a calibrated generator of sufficient accuracy 
can be brought into use. tune it in on a receiver, 
and tune the home-built generator to the same 
frequency, marking the scale. Remember that the 

— continued on page 769 
759 



Imported Receivers 

With reference to Mr. Pryse's letter 
on page 564 of the December issue of 
Practical Wireless, I should like to 
clarify a few points. 

Lafayette receivers are NOT manu- 
factured in New York, they are made in 
Tokyo, Japan, for their own subsidiary 
in New York which merely acts as an 
outlet to the trade. However, I do feel 
that the retailers in the U.S. could have 
replied though Mr. Pryse states to the 
contrary. This may be due to his letter 
having been referred to Japan. 

Further to the above remarks, I think 
that the British dealers who sell know- 
ingly Japanese products under the guise 
of American ones deserve exposure, and 
do not accept ignorance of facts as an 
excuse. No self-respecting dealer buys 
from an unknown source — though with 
what I think is junk being offered in the 
way of so-called kits, I do not believe 
that there can be many self-respecting 
radio component dealers in this country. 

Cpl. T. K. Offord. Shrewsbury, 

Shropshire. 

Communications through 
the ground 

Some time ago I made some experi- 
ments with 4 watt amplifiers for ground 
communications. I found that 200 yards 
was about the limit of these amplifiers. 
I then tried using a pair of AC2PEN DD 
valves in push-pull; this being little 
better. When I added a d.c. bias to the 
signal, I was received slightly more than 
half a mile away. (My earths are about 
30 yards apart.) 

I then thought of discarding my 
equipment which was made up of bits 
and pieces from the junk box and invest- 
ing in some new components with which 
to build a somewhat more powerful 
circuit suited better to ground com- 
munications. 

Before taking this step, I thought it 
wise to make sure that the use of high- 
power transmitters would not contravene 
any of the GPO licensing laws, so I 
wrote to the GPO at St. Martin's-Le- 
Grand, who informed me. and I quote, 
"that this particular system is licensable 
under the Wireless Telegraphy Act of 
1949. Before we could consider an 
application for a licence authorising its 
use, we should need to know the purpose 
of the installation and the type of 
messages you would propose to pass." 

I hope that this information may be 
of use to those readers who may dabble 
in the fascinating subject of Ground 
Communication. 

A. J. Clapton. Trowbridge, 

Wiltshire. 



NEWS AND 



AUTOMATIC/MANUAL TURNTABLE UNIT 




The UA70 is a new auto/manual unit designed by BSR. The 11 in. 
diameter turntable is driven from a dynamically balanced, four pole 
induction motor located on butyl rubber mountings. The low mass 
pickup arm, supported on horizontal ball bearing pivots, is of lightweight 
tubular aluminium and is counter-balanced vertically and laterally. 
After balancing, the stylus pressure is set by a rotary stylus pressure 
control calibrated from — 6 grammes. A mechanical cueing device 
allows the pickup to be raised or lowered at any selected point on a 
record when it is played manually. 

Another feature is the automatic pickup lock which secures the arm 
to its rest when a record has been played. 

Any standard mono or stereo cartridge may be fitted but the BSR 
C1 ceramic cartridge is ideally suited to this unit. Wow is below 0-2% 
r.m.s. Flutter, below 006% r.m.s. and rumble is —29dB at 1kc/s. 
Finish is in satin black with black turntable mat inlaid with brushed 
aluminium rings. Price is £12. 18s. 3d. without cartridge. 

"BUYING SECONDHAND" 

"Buying Secondhand" is one of the newest in the Consumers' 
Association paperback Consumer Publications series. It 
suggests where to look and what to look for when you are 
buying anything from a camera to a sewing machine and from a 
television set to a golf club. The section that deals with the 
buying of secondhand radios and TV's is of great value to the 
non-technical as it points out all the snags and pitfalls that 
one may fall into. It makes clear all the points that one may not 
at first look for and think of when making a purchase and we 
think that this book would be an invaluable addition to most 
people's bookshelves. The price is 8s. and it is obtainable from 
any bookseller or from the Consumers' Association, 14 Buck- 
ingham Street, London, W.C.2. 



760 



..COMMENT 



THE EXHIBITION THAT WASN'T! 

Britain's first National Hobbies Fair opened at the Royal Horticultural 
Society's Hall in London on November 12th. The- exhibition terms of 
reference was hobbies in general — collecting of coins, stamps, models, 
etc., stands for the do-it-yourself enthusiast; boat building; pottery; 
marquetry; orchid growing — and amateur radio. 

Fired with enthusiasm we went along, principally to have a look at 
two exhibits of particular interest — the British Amateur Television Club 
and the Paddington Amateur Radio Society. When we arrived, on the 
afternoon of November 1 6, we found that the BATC had fled the scene 
due, so we were told to "lack of interest by visitors", leaving behind 
nothing but an empty stand. Shaken but philosophical we looked in 
on the display of the Paddington radio club. The stand was there all 
right, complete with the club transmitting station G3PAD/A, but the 
stand was unattended and draped in a shroud! 

Instead we went to see a demonstration of hand-operated printing 
machines which, if not of radio or TV interest, was at least still alive 
and kicking. 

A NOTE FROM MARTIN ELECTRONICS 
Martin Electronics Ltd., regret that they have fallen rather 
behind with replying to letters from customers. 

They apologise for any inconvenience that this may have 
caused readers and hope the delay will not be too long. 



NAVAL OFFICER WINS FOURTH PLACE 




Sub. Lt. D. Davies, R.N. won fourth place in an international amateur 
radio contest organised by the Certificate Hunters Club. In addition 
to winning fourth place, he won the European title in the contest, 
open to amateur radio operators throughout the world. During the 54 
hours of the contest. Sub. Lt. Davies made contact with 348 stations. 
The photograph shows Sub. Lt. Davies operating his radio station at 
his home in Msida, Malta. 



S.W. Broadcast Stations 

J refer to Mr. R. Ronai's letter in 
the December issue on page 588 attack- 
ing my letter. 

In my opinion he appears to have 
got hold of the wrong end of the stick. 
I was not talking about non-broadcast 
assigned frequencies when referring to 
Radio Moscow and the like. 

The point is that Radio Moscow and 
others are deliberately filling up the 
Broadcast Bands with distorted modula- 
tion jammers which instantly wipe out 
stations on at least two adjacent 
channels — in Cyprus, for most of the 
time the 25m band was completely use- 
less. 

I do not care what frequency a s.w. 
broadcast station uses so long as it is 
not in any Amateur Band and in this 
respect I boycott the 7-0— 7-lMc/s fre- 
quencies of Radio Pakistan, Radio 
Peking, Cairo Radio and any others 
who have the nerve to use Amateur 
Band frequencies. 

As for the 18150 and 12095kc/s fre- 
quencies of the BBC, I immediately 
spring to their defence as I find in winter 
that these are the only channels usable. 

I am not demanding that you should 
stop mentioning these stations, but I 
feel that if you really cared you would. 
N. D. Mugford, A4713 Anglesey, 

(ex ZC4) North Wales. 



Ancient and Modern 

I would be interested to learn if any 
other readers have successfully fitted a 
modern pickup to an early cylinder-type 
gramophone. I have an Edison model 
circa 1890 with a number of wax 
cylinders, most of which are in mint 
condition. 



A.W. Jenner. 



53 Clifford Way, 
Hounslow, 
Middlesex. 



Wireless Set 31 

I will shortly be getting a 31 set, and 

I would like to ask other readers if they 

have any useful data on this unit that 

they could lend me. These sets are 

advertised as breakdown units, but I 

would like to get one working rather 

than break it down for spares. 

Charles Cawley. 15 Willow Walk, 

Dog In Tree Estate, 

Huntington Cannock, 

Staffordshire. 



761 



eractically 
/ireless 

commentary by 



HENRY 



No. 30 

"Whobody 
did it" 



THE prime advantage of 
sitting on a fence is the all- 
round view one gets. A 
service mechanic who is also an 
inveterate spare-time dabbler 
treats with greater sympathy the 
customer bringing electronic 
oddments for repair after having 
had a go— and failing. He knows 
too well the pitfalls and frustra- 
tions of kitchen-table surgery. 

Not so sympathetic the super- 
professional, with his spot- 
checks, stock faults and instant 
diagnosis. Between him and the 
amateur there is a constant love- 
hate relationship. From his posi- 
tion on the rails, like a cowpoke 
at the rodeo, Henry watches 
them react with an air of detach- 
ment. 

The pathetic, defunct receiver 
lands on the workshop bench 




Like a cowpoke at the rodeo. 

and A. sniffs around it like a 
mongrel who scents an unwel- 
come visitor. He removes the 
back as if expecting some pop- 
eyed golliwog to spring up and 
surprise him. He glares at the 
works then: "Someone's been at 
it," he yells. 

True enough. Very often 
someone has; the unfortunate 
owner, in an attempt to circum- 
vent the crippling charges that 



service carries in these times. 
Without test equipment, spares 
and experience he is handi- 
capped. While he may make his 
preliminary tests with confi- 
dence, there comes a stage when 
he is beaten. It is easy enough 
in a well-equipped workshop to 
whip a valve from the rack to 
make a proving test — not 
so simple for the chap who has 
to justify the inroads into the 
family budget. And then dis- 
cover the fault lies a lot deeper 
and the expense was not justified 
after all! 



It sometimes seems that the 
chief enemy of A. is the bloke 
who ultimately pays his wages, 
the customer. He is angered by 
the substitute component dang- 
ling precariously from a tag- 
strip, affronted by an obviously 
"surplus" valve, offended by 
crystalline solder joints while one 
of those emergency circuit alter- 
ations (which may even be an 
improvement on original design) 
he regards as a personal insult. 

But while A. is aggrieved at 
the outsider's attempts, B. is 
almost apoplectic. He has the 
"Whobody did it?" complex 
developed to a fine degree. At 
the first sign of tampering, he is 
likely to threaten to down tools. 
Something of a perfectionist 
himself, he cannot bear the sight 
of someone else's bungling. It 
takes all the Service Manager's 
diplomatic guile ("Get at it, 
mate!") to make him deal with 
a radio set that has "bounced". 

For the benefit of innocent 
readers who imagine that the 
radio workshop is a magic cave 
whence issue perfectly reju- 
venated receivers it should be 
explained that the "bouncer", 
the "reject", the "comeback" the 
"second complaint" or "twicer" 
is the repair job that has been 
delivered and subsequently fails. 



It does happen — yes, really, even 
in the best organised department. 
Knowing the bits and pieces 
that go into the average item of 
electronic equipment, it is not 
surprising that the occasional 
failure crops up. But the custo- 
mer whose precious tune- 
box develops apparently similar 
symptoms is likely to be queru- 
lous when bringing the bouncer 
back. 




'B' is almost apoplectic. 



Listening to B. argue that the 
trouble is an Act of God is a 
treat the rest of the workshop 
rarely likes to miss. But hearing 
his remarks afterwards, when he 
discovers that the knobs are 
screwed on askew, the fastening 
bolts cross-threaded and maybe 
the valves plugged into the 
wrong sockets is a banquet of 
outraged invective. "The blighter 
isn't getting this done for 
nothing," he fumes. 

Again for the benefit of the 
innocent, remember that repairs 
carry a limited guarantee. 
Limited, that is, to the work that 
has actually been done. When 
you take your car to the garage 
for a carburettor job and get a 
puncture as you drive home, you 
would hardly expect a sympa- 
thetic response if you rang up the 
mechanic to complain. 



762 




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THE BROADCAST BANDS 



by JOHN GUTTRIDGE 



IF you want the real DX contact you will have to 
work for it this month, especially after dark. From 
1900/2000 onwards you can forget the 13, 16, 19 m. 
bs. If you wait for the late evening the 49 m.b. can 
produce surprising results with low-powered South 
Americans breaking through the strong European 
signals. If your ears can stand straining through c.w. 
the 90 m.b. is providing some rare catches. 

MIDDLE EAST 

Israel: Kol Israel (Broadcasting House Jerusalem), 
has dropped its Sunday morning English transmissions. 
The evening transmission to the U.K. has been re- 
timed to 2115-2120 on 9.009/9,725. The African 
English transmission remains 2015-2030 on 9,009. 

Turkey: Radio Ankara (Ankara), has been heard 
signing on at 2330 on 9,745 in an unidentified language. 

ASIA 

Afghanistan: Afghan Broadcasting System (Ansari 
Wat, Kabul), has restarted its evening English trans- 
mission after a lapse of several years. The transmission 
from 1900-1930 has been reported on 15,225 and 1 1,865 
although some say the 25 m.b. outlet is 1 1,760. Other 
reports say the 19 m.b. has been replaced by one in the 
31 m.b. 

Indonesia: Radio Republik Indonesia (P.O. Box 157, 
Djakarta) now appears to use only 9,865 between 1615 
and 2000. English is at 1900-2000. 

Korea (P.D.R.): Radio Pyongyang (Pyongyang), has 
replaced 6,650 by 6,480 for its 1 100-1200 and 1400-1500 
English transmissions. The other frequency for these 
transmissions remains 7,580. The station's home ser- 
vice may be faintly heard during the evening on 6,290/ 
6,600. 

Malaysia: BBC Far Eastern Relay Station (P.O. Box 
716, Johore Bahru), now has its own QSL card which 
is far superior to that issued by the BBC, London. 
Indeed this BBC relay outlet will give full verification 
details on the card if asked, something that London 
will not do. 

Philippines: Far East Broadcasting Company (Box 
2041, Manila), now using 11,855 instead of 15,385 
from 2330-0030. In the morning DZH8 has been heard 
signing on in English before 0900 on 11,855. 

NORTH AMERICA 

U.S.A.: Voice of America (U.S. Information Agency, 
330 Independence Avenue, S.W., Washington 20547, 
DC), now has the following English schedule to 
Europe: 0300-0730 3,980/5,965/5,995/7,200/7,250/9,540/ 
9,635/9,740/11,790; 0500-0730 6,040/15,295/1,196; 
1400-2330 3,980/7205/9,760; 1 500-22 1 5 5965; 1900- 
2215 9,710/11,760: 1830-2330 11,805; 1400-2215 15,205; 
1400-2000 15.290; 1400-1830 17,780; 1600-1800, 2100- 
2130, 2200-2330 1,196. On Sundays read 2345 for 2330. 



A new programme format is being used by the V.O.A. 
U.S.A.: Radio New York Worldwide (485 Madison 
Avenue, New York, N.Y., 10022), now uses the follow- 
ing frequencies to Europe in English: 1200-1400 15,265/ 
17,845; 1400-1600 15,440/17,845; 1600-2100 15,440/ 
1 7,755 ; 2 1 00-2 1 30 1 5,440/ 1 1 ,970 ; 2 1 30-2330 (-0030 Sun- 
days) 9,655/11,970; 0030-0100 Sundays 9,655. 

CENTRAL AMERICA 

Cuba: Radio Habana Cuba (Apartado Postal 7026, 
Habana). now transmits in English as follows: 2010- 
2140 (Northern Europe) 6,015; 2050-2150 15,270/ 
15.300: 0100-0600 11,760/6,170; 0330-0600 6,135; 
0630-0800 9,655; 1800-1900 15,340. 

Netherlands Antilles: Trans World Radio (SC Zout- 
pannenweg, Bonaire) has English as follows: 0035- 
0105. 0230-0400, 1105-1235 (-1530 Sundays) on 11,815 
or 11,820; 2100-2130 (Europe) 15,130 or 15,245 or 
11,815 or 11,820. 

Windward Islands: Windward Islands Broadcasting 
Service (St. George's, Grenada). The European fre- 
quency used from 2000-2145 has been variously 
reported as 11,895 or 11,920. 

SOUTH AMERICA 

Brazil: Radio Ailtina de Bahia (Avenue 7 de Setembro 
311, Salvador, Bahia), has reactivated ZYN30 on 
15,225. Has been heard from around 2300-0130. 

Ecuador: La Voz de los Andes (HCJB), (Casilla 
691, Quito), is again using 15,115 during its 1845-2000 
and 2100-2130 English transmissions. The parallel 
frequency is 17,890. 

EUROPE 

Austria: Osterreichischer Rundfunk (Wien IV, Ar- 
gent inierstrasse 30a). Frequency schedule valid to 
0100 on 5th March is as follows: on 6,000 0430-2300; 
6,155 0500-1100, 1700-2200, 2300, 0430: 7,245 0500- 
1300, 1800-2000; 9,525 0000-0300; 9,610 1700-1900; 
9.770 0500-0800, 1100-1700, 2300-0400; 11.760 0300- 
0400; 11,895 1200-1400; 11,900 1100-1400; 15,210 
1900-2100; 15,410 0600-0900; 15,430 0000-0200; 
17,730 1400-1600; 17.750 1600-1800; 17,755 1000-1200; 
17,855 0400-0500, 0800-1000. 

Belgium: Belgian National Broadcasting System 
(Overseas Service, 18 Place Eugene Flagey, Brussels 5), 
has replaced 17,860 by the new outlet of 11,715 from 
1600-1715. At this time 9,740 is also in use. Another 
new outlet heard is 9,660 from 1830-2100. 

Thanks go this month to the Swiss Broadcasting 
Corporation, A. B. Thompson, the World Communica- 
tions Club of G.B., B. Bunting, Roy Patrick, A. E. 
Roxburgh, the International Short Wave Club, B. 
Lowe, J. D. Ashworth, J. W. Smith, B. Garvey and 
D. G. Hobro. 



765 



THE AMATEUR BANDS 



by DAVID Gl BSON, G3JDG 



AUSTRALIAN and New Zealand hams at 5 and 
9 plus on topband or just a few local G 
stations? Well, your guess is as good as mine 
for the coming year. Theoretically 28Mc/s should 
be really something and 21 should also provide 
hoards of DX. Fourteen will doubtless continue to 
provide most distant signals at one time or another, 
and of course 7Mc/s will seem noisier than ever. 
Topband and Eighty may well go down into the 
doldrums with the seasonal changes and the sun- 
spot activity increase. 

What about those New Year resolutions? All 
those not making any are banished to 7Mc/s. Still 
stuck for ideas? How about the station itself. Does 
your antenna go to ground when you switch off? 
How about fuses, and those mains plugs, are they 
100%? Has the earth lead corroded? This can be 
a source of noise. First resolution then, check the 
entire installation from mains right through to the 
aerial itself. If you do this just once a year it 
will avoid your wondering why you don't hear the 
DX too well, only to find when you do check, 
that the antenna wire broke off at the window, 
giving you an effective length of 3|ft. (Pauses, 
titters behind fan, and remembers case of the 
"3IDG "longwire" which wouldn't load.) This month 
there appears to be a mass migration to ten metres. 
Certainly the band has been wide open most days 
although it does fall off at night. If things continue 
we will doubtless end up with the spottiest sun for 
decades. In view of the many very fine logs which 
arrived I propose to move on to my New Year 
resolution — cutting of the cackle. 

TEN 

Reports from all over, from Scotland to Worces- 
tershire, all reporting the same story, DX on Ten. 
All modes, all continents too, with the best time 
to listen still during daylight hours. 

C. Clarke (Surrey), 12 valve single conversion 
s/het, phased verticals logged — K2RFZ/MM, 
K3BEQ, K8ERD, LU7ABV, MP4BBA. MP4TBO, 
OD5CN, PY2ARV, SV1AN, SV0WL, UA1AVM, 
UA3AJT, UA6LIV, UA9FFB, UB5APK. UW9CR, 
VE3FIT, VK3AHT, VK3HW,VK6CF, VP9FB, 
VS9A.TC, WIFQA, W8CNC, W9ARK, W0GYM, 
ZC4MO, ZS40I, ZS5DC, 4X4HJ, 9J2BK. Chris 
reckons it won't be long before we start hearing 
JA and UA0 on ten metres. Anyone been lucky 
yet? 

P. Baker (South Wales). HE30, 45ft. l.w. raised— 
CR4BC, many CR6's, CR7DS, CT3AM, EA6BH, 
EA8AE, JA1TRD (sorry I spoke!), K2GL, MP4BBA. 
OD5BU, PY1LW, SV1AL, UA9FB. UF6DV, 
UG6AZO, UY5HF (Ukraine— new prefix issue), 
VOIHB, VS9APW, W5GQG. W0IMC, XE2BM 
(Mexico), ZB2AJ, ZC4KF, ZE1JA, ZS1JH, ZS8L, 
ZS9G, 5A1TK, 5N2AAF, 9H1A, 9Q5EB. 

George Owen (Somerset). GC1U, Joystick, heard — 
CR4BC, CT3AM, CX1AAM, EA8EV, IT1ALD, 
K3AAG. LU2DED, PY8MA, PZ1BK, VE2BT, 
WICLP, W5GQG, ZE1BP, ZS1BS, 9Y4VS, all these 
on a.m. 

Colin Morris (Worcestershire), double s/het home- 



brew, Joystick, hooked — CR6HF, CX2CO, 
CX4AW, ET3AC, FH8CD, HK3AVK, KR6LL, 
KG6AAY, KV4CX, KP4BJM, LU1DAB, MP4TBO, 
OA4PQ, UL7JA, VK4HC, VK5QR, VK6GP. 
VK0KM (Antarctica), VP5RB, VS9AJC, all W 
prefixes, YV9AA, ZB2AM, numerous ZC4's and 
ZS's, 4X4GV, 4Z4HQ, (new prefix — State of 
Israel), 5A3TN, 5N2AAF, 5R8CQ, 5Z4AA'. 
W0GTA/8F4 (Sumatra), 9Q5BD. Colin informs 
that Don Miller has permission to operate from 
Albania, Rio de Oro, and Annobon Island. Also 
reported is great activity anticipated on Easter 
Island (CE0). W0GTA/8F4 is also trying topband. 
Many more logs for 28Mc/s but the picture can 
be seen from those quoted, so let's wander down- 
scale to — yes, the dreaded l.f. bands, 80 and 40. 

L.F. END 

C. Claydon (Scotland), 840C + preselector, 12ft. 
vertical groped in the 7Mc/s darkness for — EA4CR, 
K1HVV, SV1CX, UL7QG, 9X5MH (Rwanda), 
W1FJJ, WB2NDS. 

D. Harvey and T. Cowpe (Salop), R107, 80ft. 
wire, both assure that persistent scanning of the 
dreaded segment brings rewards. Proof offered — 
HB9ABM, 10RB/4U, JA4BJO (yes. Japan), JA6YB, 
K8ARW, KP4BRX, LX4JB, OA3KCB, OX3KV, 
UA3KBD, UA6KE, UD6BV, VP6KL, VK2AVA 
(nearly always on 40), VK3BM, W0GTA/A, 
ZC4MO. 

F. Simpson (Yorkshire), claims that 40 is like 
someone sawing an endless plank. (I wooden be 
surprised!). On the other hand 80 proved very 
fruitful with— KG4AA. OA8V, OX3JV, TF3EA. 
VOIFG, VE1IE, VE2XO, VE3WV, VP1PV, 
VP2AA, VP7DL. VP9BO, VS9AJC, VS9ALV, 
W1HKK, W2ZPO, YS1DHE, YV5BOI. ZF1GC 
6Y5EM. It's almost as good as my 21Mc/s log! 

N. Henbry (Sussex), strikes again! Armed with an 
EA12 and a 20 metre dipole on 3-5Mc/s, Norman 
logged K2DXV, K8YWG, VE1ADA. VE3AYS. 
VS9AJC, W1AQH, W2APU, W3BMS, W4S1B, 
W9JLH, YV5BTS, ZB2AJ, ZL3ACJ, ZL3GS, 
ZL4KE, ZL4LM, 7X0AH. On 7M/cs the best were 
CN8AW, CR6IV, PY1BDX, VE3LZ, VK2AVA, 
VK0AA, VP2AA, W3BMS, W4BYB, WA8DNQ, 
W0GTA/8F4, 5A1TS. 

14 AND 21 

Very, very few reports for the favourites, every- 
one seems split into two groups. The "let's listen 
on ten" brigade, and the real expert DXers trying 
their skills on 3-5 and 7. 

R. Garvey, back from Cyprus (get the umbrella 
out of pawn again, Bob) had a quick listen with 
his S640 and heard VK's on l4Mc/s at 589. His 
best for the session— EP2RV, JT1KAA, OY3L, 
TA2AC, VK2EO, VK0NB, W6MQT/OX3, ZAIBB. 

CONTESTS 

Sparse month for contest types. Only two down 
in my diary — 14-1 5th, Affiliated Societies' Contest 
(quite lively this one), 29th, 144Mc/s c.w. Contest. 
Many thanks for the fine logs, deadline for January 
is the 24th. 



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IIM. DYNAMIC (50KO) mike for stand use. Very attractive design with punched 
chrome finish. Swivel action with stand mounting brackets 48/-. P. 4 P. 2/6d. 
(suitable heavy base floor stand, telescopic: standard thread: 49/0d. Carr. 2/6d.) 

4 TRANSISTOR 3W AMPLIFIER. Size 2} x 2j x li 3. 8 or 16Q output. 9 volt 
battery operated. Highly sensitive. Price (less battery) 52/8d. 1'. A P. l'6d. 
VERNIER DIALS— fit standard Jin. spindle— approx. 8 : 1 ratio. Marked 0/100 
through 180°. Small round 2in. dla.: 10/6d. L arge 3in- dia.: 18/-. Post on either !/•■ 
MAINS TRANSFORMERS: 860/0/860, "flinA. 6v and 6.3v at 2A Chassis MTO. 
230v or HOvIN Size 4 x 3f x 2jln. 21/- ea. P. 4 P. 2/-. VOLTAGE DROPPING 
TRANSFORMER: 230 vLN, 3.5v. 9v and 12v out at 4 amps. Many uses — finest 
U.K. make. 3 x 2} x 2-;in. 22/6d. each. P. 4 P. 2/fiiI. 

RECORD PLAYER DECKS. GARRARD 

... * „ I All lilted mono cartridge. 
Joina i-Stereo 10/- extra. Carriage 



1000 



3 speed single play< 

4 speed de lnxe sint 
4 speed anto change 



H-*J-° extra, 5/- on all types, but 
so.ia.o j price | nclullc9 free gift. 



Finest Quality British made MYLAR Recording Tape. Fully Guaranteed. 
3in. 225 Message . . . . 61- 5}in. 1200ft Long Play . . 12/6 
5iu. 600 Standard Plav . . 8/8 Tin. 1800ft. Long P.ay . . 19/6 
51m. 850 Standard Play .. 11/6 5m. 1200ft . Double Play .. 15/- 
7in 1200 Standard Plav .. 14/6 5!m. 1800ft Double Play .. 82/6 
Bin 900ft. Long Play.. .. 11/8 7'n 2400ft. Double Play .. 85/- 
P. 4 P. ll-perreeLFoorreelsand over post paid. N.B — MYLAR based recording 
tape la of infinitely superior quality and far stronger than Acetate base tape. 
TRANSRECEIVERS. (Not for use in G.B.) intermediate model, complete with 
extending aerials, batteries Instructions. Really excellent results. 
Per pair £8.15.0. P . 4 P. 0/- including free gift. 

MULTI-TEST METER. Pocket size— 4» x 31 x >»/„in. 20.0000 p volt. 

D.C. Volts (20,0000 P.V.) 0/5/25/250/500/2500 D.O. Current 0-50 microamp. 

2.5mA /250mA 
A.C. Volte (10,0000 P.V) 0/10/50/100/500/1000 Resistance: 0/6kQ -0/6 megohms 
Capacity: 10 jlliF to .OOluF/.OOlLlF to .l|iF Decibels: —20 to + 22dB. 
COMPLETE with batteries, instructions, leads 7S/6d. P. 4 P. l/6d. 
Other types available from 87/66. 

TRANSISTORS: Some popular types from our range: — 

0044 4: OC45 3/6d. ea. OC71 8/9d. OC72 8/6d. OC81 4 OC81D 8/- oa. 

0C169 8/80. OC170 3/6d- AF117 4/-. 0026 7/6. GET 8 6/9. Genera! purpose 

(Approx. OC71) 1/- ea. Postage 6d. up to 3. Over 12 sent P. 4 P. paid. 

R F FIELD INDICATOR. Ideal for ate with radio controlled models. Checks 
radiation from existing antenna. Tones 1 to 250 MC in 5 bands. Sensitive 200 mi 
meter movement. 5 section plug-in aeriaL Phone Jack and crystal earpiece for 
monitoring. No battery required. Powerful magnet for attaching to metal surfaces. 

Co mplete with instructions. 47/6d. P. 4 P. 2/6d. 

TERMS Cash with order— No C.O.D. Orders totalling £5 and ovor sent carriage 
paid (excepting Record player decks and Tranareceivers where carriage is shown). 
Guaranteed money refunded If good returned perfect within 7 days of despatch. 

REMEMBER THE NOVEL FREE GD?T EXCLUSIVE TO US I 
Callert welcome— Very many more Una to choose from. Open 9.30 o.m.-6 p.m. 
Mm.— Sat. 



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■^ Volume, Tone and Treble Controls 

•^ Metal Knobs (Silver pointer marked) 

-fc Professionally designed Front Panel (Silver) 

■^f Operating/Instructions booklet 

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CEECO, 1a CARLYLE ROAD, CAMBRIDGE 



768 



Wide Range Signal Generator 



— continued from page 759 



receiver will respond if tuned to the same 
frequency. But there is no response if the gener- 
ator is tuned to multiples of the receiver frequency. 
So the fundamental frequency is the first one caus- 
ing a response if the generator is tuned from a 
high frequency downwards. 

HARMONIC STRENGTH 

Harmonics grow progressively weaker. With a 
sensitive receiver, lMc/s harmonics may be heard 
up to 30Mc/s or higher, while lOOkc/s harmonics 
can be tuned in up to about 5Mc/s. 

With a t.r.f. receiver, any response will be at 



the generator frequency, or multiples of this 
frequency. 

When using a superhet, various spurious res- 
ponses arise. They can usually be identified because 
they are weaker. Second channel effects are heard 
at a frequency which corresponds to an error of 
intermediate frequency x 2 (940kc/s for an i.f. of 
470kc/s). This is likely to be noticed at high, 
frequencies, but not at medium or low frequencies. 

Weak spurious responses also arise from receiver- 
oscillator harmonics beating with the generator 
signal. This is also usual. 

VR1 is used to adjust signal strength as 
required, but ceases to be wholly effective at high 
radio frequencies. This is unavoidable with a simple 
potentiometer. Enough signal is often secured merely 
by placing an unscreened generator output lead near 
the receiver aerial. 



TESTING and ALIGNMENT PROCEDURES 



The wide range signal generator can be used for 
many purposes, such as the quick location of faulty 
stages in audio amplifiers, or complete receivers. If 
an audio amplifier gives no results, for example, the 
source of the fault can often be found quickly by 
injecting an a.f. signal. A typical two-stage amplifier 
is shown in Fig. 6. 

With battery-operated valve receivers, or those 
having heater and h.t. from a transformer, a 
direct connection can be made to the chassis or 
earth line at A by clipping on a lead from the 
generator earth, or coaxial outer conductor. With 
a.c./d.c. or other sets alive to the mains, first check 
that the chassis goes to mains Neutral. Also include 
an isolating capacitor in the earth mentioned. 



AUDIO STAGES 

Then set the generator to give an audio output, 
and feed it into point B. If the signal is not heard, 
the output transformer or speaker is defective or 
disconnected. 

If the signal is heard, transfer the generator prod 
to C. If there is a considerable increase in volume, 
the output stage is obviously working. Then trans- 
fer the prod to D. If the signal disappears, the 
coupling capacitor or connections here are defec- 
tive. 

Should output be obtained from injecting at D, 
take the prod to E. Volume should again increase 
greatly, if the triode amplifier stage is functioning 
correctly. Then take the prod to F. If the signal 
disappears, the 1 Mil volume control or a connec- 
tion to it is suspected. If results are in order, move 
the prod to take in any pick-up or other lead 
included. 

Thus, the method is to work backwards stage 
by stage, until results cease. The last part of the 
circuit just introduced is then faulty. When the 
faulty stage is found, a meter is generally brought 
in to check resistors and other items in the defec- 
tive stage. Generator output is reduced as neces- 
sary with the output control. Pre-amplifier and 
other stages can be dealt with in the same way. 



I.F. CIRCUIT TESTS 

Exactly the same method can be used to locate-, 
a faulty stage in an intermediate frequency ampli-. 
fier, the generator being adjusted to deliver 
modulated r.f. at the intermediate frequency. With 
many receivers the i.f. is around 470kc/s. First 
test the audio amplifier as described, if necessary. 
Audio is also injected at points A and B, Fig. 7, 
to check the anode coupling capacitor. Then inject ' 
audio at C, D, E and F in turn, to check the 
triode seotion of the double-diode-triode, grid ' 
capacitor, potentiometer and 33kH diode filter 
resistor. 

Modulated r.f. can now be injected at G, and. 
the generator tuning swung around the i.f. Output ' 
at one frequency shows that i.f.t.2 is in order. Lack 
of output shows this component, or connections 
to it, are faulty. v 

With output obtained, move to point H, to check 
the i.f. stage. Output should be much increased. * 
Taking the prod to I tests i.f.t.l. Results should 
also be obtained with a signal at the i.f. injected 
at J. -- ' 

When a faulty stage is found, a meter test will . 
show if normal voltages are present. If not, the 
connection or resistor in circuit should be checked. ; 

I.F. ALIGNMENT 

With a new home built receiver, set the. gener- 
ator at the specified intermediate frequency (mbdu- ' 
lated). Should the i.f.t's. be pre-aligned or not badly ' 
off tune, inject at J and adjust their cores for best 
results. 

If the cores are badly off tune, often it is neces- 
sary to inject at G and tune i.f.t.2, then at I and 
deal with i.f.t.l. Afterwards inject at J (to remove 
stray capacity from i.f.t.l) and re-adjust both i.f.t.l 
and i.f.t.2. 

R.F. STAGES 

If a defective receiver has been tested as far as 
I and J, Fig. 2, this shows that the i,f. and a.f. 



769 



sections are working. Modulated r.f. of the 
frequency to which the receiver is tuned can then 
be injected at J. Lack of results shows that the 
mixer stage is defective. Moving the prod to K 
(with results from injecting at J) allows the 
individual coils to be checked. 

When an r.f. amplifier is present, this can be 
checked with the appropriate r.f., exactly as with 
the aerial circuit of the mixer. Fig. 7. 

To align aerial and oscillator circuits of a newly 
made receiver it is usually convenient to set band 
coverage, adjust the aerial circuit to agree, then 
trim and adjust cores for best sensitivity. For a 
typical medium waveband of about 550-1500kc/s 
this could be done as follows: 

(1) Switch to medium waves, inject 1500kc/s at 
aerial and adjust oscillator trimmer for cor- 
rect dial reading. 

(2) Roughly adjust aerial trimmer for best 
results. 

(3) Inject 550kc/s and adjust oscillator coil core 
for correct dial reading. 

(4) Roughly adjust aerial core for best results. 

(5) Inject at 1300kc/s, and adjust oscillator and 
aerial trimmers for best sensitivity. 

(6) Inject at 750kc/s and adjust oscillator core 
and aerial core for best sensitivity. 

Steps (5) and (6) are repeated until no further 
improvement can be obtained. The actual trimming 
point (5) and tracking point (6) will vary some- 
what in actual receivers, but are generally a little 
clear of the extreme ends of a band. At these 
steps the oscillator trimmer and core need not be 
altered unless a compromise is needed with the 
accuracy of dial readings. 

Any r.f. stage coils can be dealt with in the 
same way as the mixer aerial coils. Fig. 7. With 
completely separate coils for each waveband, deal 
with each band individually, afterwards checking 
all bands. With long/medium wave coverage by dual- 
band coils or ferrite aerials, it is usually necessary 
to adjust medium waves first. 




Fig. 6: Test points on a typical audio amplifier. 



OUTPUT INDICATION 

If tuning is by ear, keep the generator output 
as low as possible for final adjustments, with the 
receiver audio gain at maximum. Otherwise the 
any a.g.c. circuits will mask the effect of adjust- 
ments. 

An audio output meter is often handy. The 
simplest comprises a crystal diode in series with 
a multi-range meter, which is connected across the 
output transformer primary or secondary. Set the 
meter to a suitable d.c. range. Some meters can 
be used without the diode by switching to an a.c. 
range. 

It is sometimes convenient to adjust tuning or 
i.f.t's. for minimum anode current in an a.g.c. 
operated stage. To avoid interrupting permanent 
wiring, a multi-range meter can be clipped across 
one of the cathode resistors in Fig. 7. Either 2-5, 
5 or 10V range is usually satisfactory, according 

— continued on page 773 



V 



33k n 



-rum 





•27k.fl 






12AH8 



!0-05jjF 



0«05>jF! 



200pF 



100pF 




!220rL 



005 



I 



100kfl 

--vww 




1Mfl 

-wwv 



Fig. 7: Test points on a typical radio receiver. See text for details. 



770 



RADIO • HI-FI • COMPONENTS • TEST EQUIPMENT 



TT.144 DYNAMIC 

TRANSISTOR 

TESTER 

Tests in-clrcult _. 
out of circuit. Identi- 
fies PNP and NPX 
types. Indicates 

electrode open cir- 
cuits, short circuits 
and current drain. 
Complete with in- 
struction.", 

£4.10.0 



TT.145 DE-LUXE TRANSISTOR 



ALL ITEMS SENT POST FREE 




DIODE TESTER 



£9.7.6 



MULTI METERS 

T.30A 1.000 o.p.v. £2.18.6 

TK.26 1,000 o.p.v. £2.15.6 

EP.10K lO.OOOo.p.v £4 17 6 

EP.10KN 10,000 o.p.v £5.8,0 

EF.20K 20.000 o.p.v £5.18.6 

BP.20KH 20,000 o.p.v £6.8.0 

EP.30K ;io,0(i(io.p.v £7.19.6 

EP.30KS 80,000 o.p.v £9.0.0 

EP.50KN60,000o.p.v £11.19,6 

EP.100KJJ 100,000o.p.v. £14.19.6 




TE-188. RF SIGNAL GENERATOR 

A stable wide range signal generator 
with a range of 120 KcM-260Mc,'s on 6 
bands. Features a large 41in. vernier 
tuned, etched circular dial for easy 
accurate frequency adjustments. 
Complete with f"Of\ 1 C f\ 

instructions. I-4U, I O.KJ 

TE190. SINE SQUARE WAVE 
AUDIO GENERATOR 

SINE WAVE: 20-200.000 cps in four 

bands. 

SQCABE WAVE: 60-30,000 cps. Input 

impedance 0-5,000 ohms. Especiallv 

designed for HI-FI Radio and TV 

Service men who require a dependable 

instrumeut. f p-t 1 Q C 

RF. 40 RF FIELD INDICATOR 



Broad tuning 



Mc/s in five 
calibrated 
bands. Can 
also bo used 
as frequency 
checker. De- 
tects undo- 
sired radia- 
tion or spur- 
ious frequen- 
cies. RF Is 

£4.10.0 



TAPE HEAD OEMAGNETIZER 
MODEL TO. 79 

Compact, easy 

to handle. Will 

mag- 





itism 
tape heads per- 



mitting improved recordings. Redi.__. 
harmonic distortion and noise level, 85/6. 
Also Two Probe version TD.I09, 38/6 







SR165. ALL BAND 
COMMUNICATION RECEIVER 

This entirely new professional type communication 
receiver features frequency coverage of 535 Kc/s- 
30 Mc/s for complete general coverage. In parti- 
cular ham bands are arranged In the same calibra- 
tion scalo, so that the band switching can be 
accomplished rapidly. fAR O fl 



UD40H CARDOID 
DYNAMIC MICROPHONE 

» a pop- 
proof diaphragm 
and superior anti 
feed-back proper- 
ties, reduces feed- 
back and room re- 
verberation. O/p: 
— IS do. Res- 
ponse: 60- 
12,000 cps: 
50K ohm im- 
pedance £6.6. 




DM3IC. CARDOID, 

DYNAMIC 

MICROPHONE 

Superb quality with 
ball head for distri- 
buted cardoid front- 
al pick-up. Output: 
— 5'Jdb. Response: 
40-13.000 cps. 
Impedance 50k ohm. 
£7.7.0. 



DM24HL 





27 other microphones available. 
EAGLE SA100. 10W INTEGRATED STEREO AMPLIFIER 

A compact, versatile Integrated 
unit for monaural or stereophonic 
reproduction from record olaver, 
tape recorder and tuner. Power 
output 5 watts per channel. Fre- 
quency response 40-20.000 o.pj. 

£18.0.0 

EAGLE AFM100. AM-FM TUNER 

Combines a host of advanced features that easily make it the finest AM-FM tuner in its 
etas* A tuned RF stage on FM. AFC circuit and a heavy flywheel giving smooth but 
™» tuning, built in AM Ferrltc aerial. F5l.S5-10B.Mc. (")n r\ n 
AM 53O-1605 K/s. I_/-C/,U.U 

MS80. 20W ROSEWOOD SPEAKER 
SYSTEM 

The perfect answer for the music lover who wants full range 
fidelity in a compact system. Features an 8ln. full range 
high compliance speaker with an output capacity of 20 watts 
RMS. Frequency response: 30-20,000 c.p-s. Resonant 
frequency: 30-40 c-p.s. Sensitivity: 97 db/w. Flux 
density: Over 12,000. Impedance: i6 ohm. She 14iin. 
high xl0 s /„in. wide x8in. deep. f 14 140 

As well as this beautifully designed speaker there are two 
other models MS«B. 10 watts RMS at £12.12.0 and MS40 
5 watts RMS £8.10.0. 

All three speakers are finished in magnificent rosewood and 
the entire cabinet filled with acoustic damping material. 

EAGLE PRODUCTS 

MAGNETIC STEREO CARTRIDGES 

M1007G GOLD 
Response: 20-20.000 cps 



Output: GMV at lKc/ 

5cm/Sec- 
Stylus: 0.6 Mil diamond 
Tracking Pressure 

1-2.5 grams. 

£6.12.6 



M1007F. SIXVER 

Response: 2ii-i s. ono cps 
Output: 10.MV at lKc/ 

Bon Bo . 
Stylos: 0.7 Mil diamond 
Tracking Pressure 

2-4 grams. 

£5.14.6 




As reviewed in Hi Fl Xcwt Sept. 1965. 

Both feature singularly smooth reproduction and incisive separation of stereo channels 

AIWA. TP. 1002. 

2-Speed. 4-track mains 
and Battery Stereo Tape 
i Recorder. The first com- 

pletely self-contained 2-speed 
stereo tape recorder, operating 
on batteries and AC mains. Uses 
Bin. reels for extra long recording time. 
Two speeds offer greatest tape economy 
plus high fidelity recording. Five 
push-button controls. Stereo inputs 
are provided for the two micro- 
phones and for two high level signals, 
such as radio, record player, TV, 
etc. One microphone has start-stop 
switch for remote control. 

complete 44 Guineas 

Also available MODEL TP 712 (Mono), 
26j guineas. 




Ba WTOMm U OF THESE AND MANY OTHER ITEMS SEND FOR FREE 

f38ggS3K&3&££H&L eagle news and order form a£l items 

AVAILABLE P08T FREE AND COVERED BY 12 MONTHS' GUARANTEE. 



CALLERS WELCOME AT OUR HI-FI SHOWROOM 



LA9P. AC ELIMINATOR 



with adouble wound step down transfor- 
mer to operate 9v Radios, ft O C 
etc.. from AC Mains. *- ■ .0.0 



RELDA RADIO LTD 

(Dept. P.W.14) 87 Tottenham Court Road. London, W.I. 




EAGLE FMT41. FM TUNER 

Bub-miniature 6 transistor 3 diode F.M. 
Tuner. Covers 88-108 Mo. Operates 
from 9-volt battery, micro miniature 
circuit giving brilliant FM reception. 
Ready to use, simply connect to your HI 
Fi amplifier. Instructions supplied. 

£8.10.0 




MCK.2. MORSE CODE KIT 
Two station morse code kit supplied 
with instructions, 80ft. of connection 
wire and morse code A?"l 1 f\ 
charts. L-i.Z.U 

H.T. 20 Rectangular Horn Tweeter 

Ideal for 2- way 
and 3 - way 
speaker sys- 
tems ensuring 
smooth and 
clean repro- 
duction. Out- 
put 20 watts. 
Impedance 16 
ohms. Re- 

sponse 1,500 — 
1S.0O0 cps. 
£4.2.6. 

CROSSOVER NETWORK CN23, 3SJ 2 
way 14/6. CN216, 16 0, 2 wav, 14/6. 





ALL TRANSISTOR MONO & 
STEREO PRE AMPLIFIERS 

Provide extra stage of amplification for 
use with magnetic cartridges, tape and 
microphone inputs. Both models 
feature wide band pass range. 20-20.000 
cp-<. A- reviewed m Th» Gramophone, 
Dec. 19.5H. r ^ 

l'RE 801 MONO £4.12 6 
PRE 302 STEREO £5.15,0 




WI-2. TRANSISTORISED 
WIRELESS INTERCOM 

No wires, no installation needed, 
simply plug them Into AC power 
point and talk. Units have press- 
to-talk lock switch and on-off volume 
control. Ideal Intercom or Baby Alarm 

££S e ' offloe ' £14.12.0 °s 

DP303. DOOR PHONE INTERCOM 

Ultra sensitive transistorised Intercom 
designed so that you may answer 
the door from within for greater 
— vciiience and safety. 
Sther lu 
available. 

WIRELESS MICROPHONES 

WM909 (as Illustrated) 
Pocket FM Wireless 
transmitter complete 
with tie-pin microphone. 
Transmits clearly up to 
100 yds. and is fully 
tunable over the entire 
FM band. Simply used 
with an FM radio or 

tuner £14.0.0 

Also available WM808 

£21 .0.0 

Professional stick type 

FM Wireless Microphone. 

cannot be operated m U.K. 




771 



SOLDERING INSTRUMENTS 

With re -styled nylon moulded handles 



LITESOLD 
instruments 
are compact and 
nicely balanced. Bits 
are spring-collet moun- 
ted for firmness and easy 
removal. Copper bits are stand- 
ard, in sizes from -&" to H" dia. 
PERMATIP bits are slightly slower, 
but eliminate bit face wear. LITESOLD 
elements are encased in specially pre-oxidised 
wire for constant temperature regulation from 
new — less glamour but honest design, also apparent 
in the simple, unbreakable handle, with the element unit 
secured by two self-tapping screws (servicing couldn't be 
easier) and firm, spring-on clip. LITESOLD hollow-spindle 
construction prevents heat loss into the handle (which DOES 
stay cool) and improves performance. Useful LITESOLD accessories 
include HEAT GUARDS for elements, and BENCH STANDS. 

Free details of the whole wide range of LITESOLD and ADAMIN soldering equipment in brochure SP10. 

LIGHT SOLDERING DEVELOPMENTS LTD. 

28, Sydenham Road, Croydon, Surrey Telephone: CROydon 8589 and 4559 



• SEVEN SIZES from 10 WATTS to 55 WATTS 

• REPLACEABLE BITS, COPPER & PERMATIP 

• EXCELLENT TEMPERATURE REGULATION 

• COOL, UNBREAKABLE HANDLE 

• RAPID HEATING 

• SIMPLE SERVICING 

• ALL VOLTAGES 

• LOW COST 




GOODMANS 

HIGH FIDELITY 

MANUAL 

A Guide to full 
listening enjoyment 



new HAXAMPS30] 



The Manual Is much more than a cata- 
logue ol Goodmans High Fidelity Loud- 
speakers— il contains informative articles. 
Including advice on stereo, special begin- 
ners page, and full cabinet drawings. 
You'll find it Interesting as well as 
informative. 

HIGH FIDELITY 
AMPLIFIER 

MAXAMP 30 is a fully transistorised stereophonic High Fidelity 
Amplifier using Silicon Transistors throughout. It is precision engin- 
eered and fullest use is made of printed circuits. It will deliver 
continuously up to 15 watts of power on each channel and it looks 
as good as it is. 10i"x5i"x7±" £49.10s.0d. 

Full specification of the Maxamp 30 is given in the High 

Fidelity Manual - send the coupon foryour FREE copy 

- or pay an early visit to your Goodmans dealer. 



FREE Please send Hi-Fi Manual together with name and address 



of my nearest Goodmans dealer. 



■ Name 

I Address. 



PW2/67 



GOODMANS INDUSTRIES 

AXIOM WORKS • WEMBLEY • MIDDLESEX Tel: WEM 1200 

A Division of Radio Rentase; Products Ltd. 



YOUR CAREER in 

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ELECTRONICS ? 

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in every field of Electronics today — both in the U.K. and 
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R.T.E.B. Servicing Certificates; etc. Also courses in Tele- 
vision: Transistors; Radar; Computers; Servo-mech- 
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with equipment. We have OVER 20 YEARS' experience 
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BRITISH NATIONAL RADIO SCHOOL 






772 



Wide Range Signal Generator 

— continued from page 770 



to the valve and bias resistor. All trimming, core 
and i.f.t. adjustments are then directed towards 
minimum anode current, corresponding to mini- 
mum voltage on the meter. Unnecessarily strong 
signals should not be used. 

When a.g.c. is from the i.f. anode, as in Fig. 7, 
the secondary of i.f.t.2 does not usually peak for 
maximum a.g.c. voltage (minimum i.f. stage anode 
current). It should then be peaked for maximum 
audio output. With some circuits this agrees with 
a slight dip in a.g.c. voltage. 

COUPLING TO RECEIVER 

For accurate alignment, coupling must be very 
loose. Enough input may be obtained for final 
adjustments by placing the output lead near the 
receiver aerial. Some receivers are supposed to be 
aligned with particular aerial pads or loads, such 
as a 400ft carbon resistor. Or the aerial trimming 
can be touched up, if necessary, when the aerial 
is connected. The generator lead should not be 
taken directly to any i.f.t. or tuned circuit which 
is being finally adjusted because the stray capacity 
will cause errors. Proper trimming tools should be 
used, not screwdrivers having only an insulated 
handle. 

DIAL CALIBRATION 

Tuning scales can be marked up for home built 
receivers by setting the generator to various 
frequencies, adjusting the receiver to them, and 
marking the dial. If the procedure detailed for cali- 
brating the generator originally is noted, there will 
be little chance of errors from tuning in harmonics, 
or similar mistakes. 

It is sometimes required to calibrate a narrow 
band on the receiver with great accuracy. This 
can be done by tuning the generator to a much 
lower frequency, and multiplying its output by the 
appropriate figure. 

The 80 metre Amateur band provides an 
example of this method. This band is 3-5-3-8Mc/s. 
Locate 3-5Mc/s on the receiver by setting the 
generator to this frequency. Some error, due to 
visual reading, is most likely, but this 3-5Mc/s 
point is only temporary. The generator can then 
be tuned to lOOkc/s so that its second harmonic 
is at zero beat with the BBC Light Programme on 
200kc/s. A transistor portable or any convenient 
receiver can be used for this comparison of gener- 
ator harmonic and BBC. The generator is now pro- 
viding lOOkc/s to a high degree of accuracy (so 
long as it remains at zero beat with the Light 
Programme) and harmonic marker pips will be 
tuned in at 3-5, 3-6, 3-7 and 3-8Mc/s with the 
Amateur band receiver, and can be written on its 
scale. 

The upper limit to which low frequency har- 
monics may be detected depends on the receiver. 
For normal accuracy, harmonics need not be 
employed and the generator is tuned directly to 
the wanted frequency. ■ 



RECEIVER FOR 144 M/cs 

— continued from page 755 



slowly with an insulated tool, while checking cover- 
age. 

With VR2 near maximum, slowly turn up VR1 
from its minimum position. When super-regenera- 
tion commences, a loud hiss will be produced. 
Turning back VRI a little reduces this hiss, but 
if VRI is rotated too far, super-regeneration will 
cease. With VRI in the best position, VC1 can 
be peaked for maximum noise even with no aerial 
connected. With an aerial on, tuning VC1 should 
give quite a high noise level. With TCI nearly open, 




Under chassis view of the completed receiver. 

resonance with VC1 can be expected around mini- 
mum capacity, increasing slightly as VC2 is closed. 

When a usable signal is tuned in, the hiss should 
almost completely cease, and in these circum- 
stances, peaking VC1 for maximum signal strength 
corresponds to minimum noise. With careful 
adjustment, very weak signals can be resolved. 

If super-regeneration is not satisfactory, it may 
be worth changing R4 since surplus 6C4 valves 
seem to vary somewhat. If super-regeneration is 
absent, reduce R4 slightly in value. Alternatively, 
slightly increase the h.t. voltage by increasing the 
value of RIO, or reduce the value of R9. On the 
other hand, should super-regeneration be difficult to 
control, slightly increase R4 in value, or reduce 
the h.t. voltage. 

For a range of some miles, a vertical |-wave 
aerial will do. This is about 19in. long. Signal 
strength at other than short range will be much 
improved by using a dipole. It may be wire sup- 
ported from convenient points, or attached to 
insulators on a strip of wood, or self-supporting 
rods. The overall length is about 38in. In view of 
the very small size, a simple "X" or "H" aerial 
is also easily constructed, but some means of 
rotating it will then be needed. Various ready 
made or adjustable aerials, and multi-element 
aerials giving increased signal strength, can be 
obtained. At first, a dipole may be preferred. This 
is less effective, but has little directivity, so signals 
can be picked up from all directions. * ■ 



773 



PULSE COUNTING 

VHF RECEIVERS 

DURING the past few years a number of cir- 
cuits have been published describing the 
detection of f.m. signals using pulse counter 
discriminators. The purpose of this article is not 
to go over the already well trod ground of theoreti- 
cal considerations, but to put forward a practical 
front-end. Figure 1 shows in block form the 
various stages needed for a pulse counting type 
of v.h.f. receiver. 



Front 
end 




Rfc 

coupled 
IF. stages 




Limiter and 

pulse 

counting 

discriminator 




Audio 

and 

output 










Fig. 1: Block schematic diagram of a pulse counting type 
of v.h.f. receiver. 

Most of the circuits that have already been pub- 
lished employ crystal controlled oscillators in the 
front ends. These come rather expensive for the 
amateur — and for that matter the author. However, 
a circuit employing an autodyne frequency changer 
was located and found to be successful. This is 
shown in Figure 2. 

FREE RUNNING OSCILLATOR 

In simple terms, the autodyne frequency changer 
mixes the incoming signal with oscillations gener- 
ated within the valve itself to produce an inter- 
mediate frequency. One of about 150 kc/s is 
required and is obtained fairly easily, since the 
bandwidth of most f.m. transmissions is in excess 
of this. As far as the operator is concerned, it's 



The circuit shown 
in Figure 2 hooked-up 
to a direct-coupled 
amplifier worked first 
time and gave a good 
account of itself on all 
three v.h.f. sound 
transmissions put out 
by the BBC. 

A small amount of 
drift did occur during 
the initial warming-up 
period but subse- 
quently the oscillator 
held very firmly. The 
degree of oscillation 
controlled by VR1 is 
critical and may 
require a little patience 
to find the optimum 
point of working, but 
once set it can be forgotten. 

It is possible that the oscillator could set up 
interference with neighbouring sets, although no 
trouble has been experienced in this direction by 
the author. Should this occur, a buffer r.f. ampli- 
fier ought to be fitted to isolate the oscillator from 
the aerial. 

PROTOTYPE CIRCUIT 

For the sake of completeness, the original proto- 
type circuit is shown in Figure 3. From a quick 
glance, one can see inexpensive EF91 valves have 
been used and tuned circuits have been kept to a 
minimum. 

The inductance which may cause a little trouble 
is the main tuning coil. The author used a quarter- 
inch former, with an iron dust core, upon which 
he wound six turns of 20 s.w.g. enamelled copper 



Fig. 2: Autodyne frequency 
changer. 




Fig. 3: Complete circuit of a pulse counting type of v.h.f. tuner. 



a matter of de-tuning to one side of the centre 
frequency. It is, of course, much easier to tunc-in 
a receiver with a slow-motion drive. The reason 
for selecting a low i.f. is that one can employ direct 
coupled amplifiers and dispense with all the usual 
tuned circuits. 



wire. Due to the stray capacities, which play such 
an important part at these frequencies, it may be 
necessary to experiment by adding an extra turn or 
subtracting one to obtain the correct coverage. The 
r.f. choke in the cathode of VI has a value of 
1 5mH. D. V. Debbage ■ 



774 



DE LUXE PLAYERS 

-I-Speed Players 2-tooe 

Cabinets 17 x 15 x 8Iin. High 

dux loudspeakers and High 

Quality Amplifiers ready 

built. Quality output. Volume 

and Bass controls. 

Special instructions 

enable assembly in 

30 minutes, only 5 

wires to join. 

12months' 

guarantee. 

TO BUILD 
YOURSELF 

PORTABLE CABINET 
As illustrated to fit 
ard player 
autoahanger. 
3 WATT AMPLIFIER. 
Ready made and tested. 
With UCL82 triode pen- 
tode valve and EQ/ft 
loudspeaker. " Ja / u 

SINGLE PLAY UNITS 
BSR GU7 £4.19.6 

Garrard SRP12 £4.19.6 
Garrard SP25 £10.19.6 
Philips AG1018 £12. 9.6 
Garrard A70 £19.19.6 
Garrard LAB80 £24.19.6 
Garrard 401 £29.19.8 




SUPERIOR AMPLIFIER 
Ready made and tested. 
Guaranteed better sound. 
Fully isolated AC Mains 
Transformer 4 watt out- 
put. ECL86 triode pen- 
tode valve. Volume and 
tone controls with 
knobs. Qualil 
Loudspeaker 
AUTOCHANGE UNITS 
BSR Superslim £4.19.6 
Garrard 1000 £5. 9.6 
Garrard 2000 £6.19.6 
Garrard 3000 £8. 9.6 
Garrard AT60 with 
diecast turntable £10.19.6 



Garrard Teak Wood Base WB1. Ready cut for "JO /fi 
mounting. 1000. 2000. 3000. SP25. AT60. /fc/U 



INTEGRATED STEREO AMPLIFIER. 4 watts per 
channel. A splendid example of functional design and 
value. Gold enamel cabinet size 7 3 6m. 200 '350v. AC. 
Separate Gram and Tuner inputs. Self- f n i q c 

contained pre-amp and all oontrols. ~ ™ ' ■**■*' 



Q MAX CHASSIS CUTTER 

Complete: a die. a punch, an Allen screw and key 

Jin.14/6 I in. 15/9 liin.18/- l!in. 20/6 2 1 /j..in. 37/9 
: in. 1-1/9 lin. IS/- ltin.18/6 l;in.22/6 2 in. 44/3 
;in.l5/6 l'/, 6 in-18/- i;in.20/- 2in. 34/3 lhuq.31/6 



BARGAIN XTAL PICK-UP ARM Complete with 

ACOS LP-78 Turnover Head and Styli 20/-: Stereo 30/-. 
SPEAKER FRET Tygan various colours, 52in. wide lrom 
10/- It.: 26in. wide from 5/- ft. Samples S.A.E. 
EXPANDED METAL Gold or Silver 12 x 12in. 6/-. 
NEW GARRARD GRAM MOTORS 100-130v. A.C. 15/- 
pair for 200/250v. .in series), or 10/- each Post Free). 



FULL WAVE BRIDGE SELENIUM RECTIFIERS: 
2. 6 or 12v. outputs. 1'- amp.. 8/9; 2 a. 11/3; 4 a., 17/6. 
CHARGER TRANSFORMERS P. & P. 2 6 Tapped 200/250 v. 
for charging at 2. 6 or 12 v., 1; amps.. 15/6; 2 amps.. 17/6; 
4 amps.. 25/-. Circuit included. Amp meter 5 imp.. 10/6. 

MOVING COIL MULTIMETER TK 25. 
0-1.000 v. A.C./D.C. ohms to 100k. etc. 
MOVING COLL MULTIMETER EP10K. 
0-1.000 v. A.C./D.C, ohms to 3 meg. etc.. 
MOVING COn, MULTIMETER EP20K. 
0-2 .500 v. D.C. 20.000 ohms per volt. 0-1.000 v. A.C. 
Ohms to 6 meg. 50 Microamps full scale. 



47/6 
79/6 

99/6 



NEW MULLARD TRANSISTORS 
OC71 6/-; OC72 7/6; OCS1D 7/6; OC81 7/6; AF115 10/6; 
AF114 11/-: OC44 8/-: OC45 8/-; OC171 9/-; OC170 8/6; 
AF117 9/6. OC26 12/6: Transistor Holders 1/3. 



ARDENTE TRANSISTOR TRANSFORMERS 
D3035, 7.3 CT : 1 Push Pull to 3 ohms lor OC72. OC81. .11/- 
D3034, 1.75 : 1 CT. Pnsh Pull Driver for OC72. OC81. .11/- 
D3058. 11.6 : 1 Output to 3 ohms for OC72. OC81 11/- 

TRANSISTOR MAINS ELIMINATORS 
Famous "Power-Mite" 9 volt. Same size as PP9 /IC/_ 
battery. Fully smoothed, full-wave circuit. "WP/ 



WEYRAD P50 — 

RA2W 6 in. Ferrite Aerial 
with oar aerial coil .... 12/6 

Osc. P50/A10 5/4 

470 k/os I.F.P50/2CC. . . .5/7 ' 
3rd I.F. P50/3CC 6/- I 



Transistor Coils 

Spare Cores 8d. 

Driver Trans. LFDT4 9/8 

Printed Cirouit, PCA1 9/6 

J.B. Tuning Gang 10/6 
Weyrad Booklet 2/- 



V0LUME CONTROLS 

Long spindles. Midget Size 
5 K. ohms to 2 Meg. LOG or 
LIN. L/S 3/-. D.P. 5/-. 
STEREO L/S 10/6. D.P. 14/6. 



80 ohm Coax 6d yd. 



Semi 
40 yd. 



air-spaced Cable 
17/6. 80 yd. 26/-. 



FRINGE LOW LOSS. 
Ideal 625 lines, yd. 



1/6 



COAXIAL PLUG 1/-. PANEL SOCKETS 1/-. LINE SOCK- 
ETS 2/-. OUTLET BOXES. SURFACE OR FLUSH 4/6. 
BALANCED TWIN FEEDERS 6d- yd.. 80 or 300 ohms. 
TELESCOPIC CHROME AERIAL. 6in. extends to 23 in. 6/6. 

TV REMOTE CONTROL 

For Philips 19TG111A. 121A, 
125A, 142A, 23TGU1A. 113A, 
121A. 131A. Stella ST1033A. 
39A, 43A. 53A. Cossor 
CT1910A, 21A. CT2310A, 21A. 
31A. Philips Price 3 gns. 

Our 1 O / fi Post 

Price ' *•< v Free 
Brand New. Includes lift. 
7-way oable. Mullard OA81 
2 pots, 3 switches, 5 resistors. 




STELLA RECORD PLAYER AMPLIFIER 

4 watt. 2 stage. 3 to 7 ohm. Neg. teed back. UCL82. UY85. 
200-250v. A.C. tapped input. Chassis size 8 2: 4in. high. 
Gold/Walnut knobs. Volume and Tone controls on separate 
Polished Wood Panel 8 • 2in. Brand new with lO/C 
makers' guarantee. Bargain price. P. & P. 1/6. #•»/«» 



NEW TUBULAR ELECTROLYTICS 
100/25 v. .. 2/- 
250/25 v. .. 2/6 
500/15 v. . . 8/- 
8 + 8/450*. 8/6 
8 + 16/450 v. 8/8 
16-16/450 v. 4/3 
32 • 32/350 v. 4/9 



2/350 


. 8/3 


4/350 V. 


. 2/3 


8/460 v. 


. 2/3 


18/450 v. 


. 8/- 


32/450 v. 


. 3/9 


25/25 v. 


. 1/9 


50/50 v. 


. 2/ 



CAN TYPES 
8/600 v. 6/6 

16/600 v. 12/6 

16 - 18/500 v. 7/6 
32 -32/450 v. 8/- 
50 • 50/350 v. 7/- 
64-100/350V. 11/6 
100 - 200/275V.12/6 



PAPER TUBULARS 
350v.-0.1 8d.. 0.5 1/9; 1 mid. 8/-: 2 mid. 150v. 3/- 
500v.-0.001 to 0.05 9d. : 0.1 1/- : 0.25 1/6 ; 0.5 3/-. 
l,000v.-0.001. 0.0022, 0.0047. 0.01. 0.02. 1/6: 0.047. 0.1 2/6. 

E.H.T. CONDENSERS. O.OOlmfd.. 7kV., 6/6: 20kV., 10/6. 
SUB-M1N. ELECTROLYTICS. 1. 2, 4, 5. 8, 16. 25. 30, 60, 100, 
250mfd. 15v.. 2/6; 500. lOOOmfd. 15v.. 3/6; 2.000mfd. 25v., 
7/-. CERAMIC 500v. 1 pF. to O.Olmfd.. 9d. 
SILVER MICA. Close toleranoe iplus or minus ( pF.), 5 to 
47 pF..l/-; ditto 1°; 60 to 800 pF. 1/-; 1.000 to 5.000 pF., 2/-. 
TWIN GANG. "0-0" 208 pF. - 176 pF.. 10/6 ; 365 pF.. minia- 
ture, 10/-; 600 pF. standard with trimmers, 9/-; 600pF 
midget less trimmers. 7/8 ; 500 pF. slow motion, standard 9/- ; 
small 3-gang 500 pF. 18/8. Single "O" 365 pF. 7/8. twin 10/- 
SHORT WAVE. Single 10 pF., 26 pF,, 50 pF., 75 pF.. 
100 pF., 160 pF.. 6/6 each. Can be ganged. Couplers 9d. each. 
TUNING. Solid dielectric. 100 pF., 300 pF., 500 pF., 3/6 each. 
TRIMMERS. Compression oeramic 80. 50, 70 pF.. 9d.; 
100 pF., 150 pF., 1/3; 250 pF.. 1/6; 600 pF.. 750 pF., 1/9. 



SPECIAL OFFER! NEW B.A.S.F TAPE 
7 in. L.P. 1,800 ft. (Cat. LGS35) 45/- 
7 in. D.P. 2,400 ft. (Cat. LGS26) 70/- 

Spare Spools 2/6. Tape Splicers 5/-. Leader Tape 4/6. 

Tape Heads: Collaro 2 track 23/6 pair. B.S.R. 4 track 99/6. 



MAINS TRANSFORMERS 



Post 
2/6 each 

E.M.I. 830-0-230. 100mA. 8.3 v. 4 a. 6.3 v. 2 a 19/6 

250-0-250. 80 mA. 6.3 v. 3.5 a. Rectifier 6.3 v 25/- 

la or 5 v. 2 a. ; Ditto 350-0-350 29/6 

MT.510 30O-O-300 v. 120 mA, 6.3 v. 4a 89/6 

MINIATURE 200 v. 20 mA.. 6.3 v. la 10/6 

MIDGET 220 v. 45 mA., 6.3 v. 2 a. 15/8 

SMALL 300-0-300 v. 70 mA.. 6.3 v. 4 a 19/8 

HEATER TRANS. 8.3 1. 1 J a., 7/6 ; 6.3 v. 4a 10/6 

Ditto tapped sec. 1.4 v.. 2. 3. 4. 5. 6.3 v. H amp 10/6 

GENERAL PURPOSE LOW VOLTAGE. Outputs 3, 4. 5, 

6. 8, 9. 10. 12. 15. 18. 24 and 30 v. at 8». 85/- 

Ditto. 1 amp.. 5. 10. 15. 20. 25. 30. 40. 45. 50. 55. 60 29/6 
AUTO TRANSFORMERS 0-115-230 volt Input/Output 
60 w. 18/6: 150w 25/-; 500 w. 82/6. 



CRYSTAL MIKE INSERTS 

It* iin.6/6:AC081i - iin.8/6:BM31 K fin 7/6 

TANNOY CARBON MIKE with Switoh 5/6 

HEADPHONES 2000 ohms 12/6. 4000 ohms 15/-. 



1967 GRAM 
CHASSIS 




£10.10. 



Three Wavebands: Five Valves: ECH81, EF89. 

Long., Med.. Short. Gram. EBC81. EL84. EZ80. 

12-month guarantee. A.C. 200-250 v. Ferrite Aerial 
5 -.vans 3 ohms. Chassis 13. in. • Tin. • 5in. dial size 
13in. ■ 4in. Two Pilot Lamps. Four Knobs. £10 10 
Aligned calibrated. Chassis isolated from mains 
DE-LUXE STEREO GRAM CHASSIS. V.H.F.. M.W. 
8.W. 19-50m. 8.W. (lO-lMOm. Magic ■■ye, uush I.iiiimi- 
(Mjmi™ plus reel. Size US , 7, , Sin. £ 19 . 19 .0 



HIGH GAIN TV. PRE-AMPLLFIER BAND 1 B.B.C. 
Tunable channels 1 to 5. Gain 18 dB. ECC84 valve. 
Kit price 32/6 or 65/- with power pack. Details 6d. 
BAND III I.T.A. same prioe. Tunable channels 7 to 13. 
Band I or III. Colls and circuit only, 9/6. Chassis 4/9. 
B.B.C.2 Super Booster. U 111" Transistor Model ready made 75/- 

BLANK ALUMINIUM CHASSIS. 18 s.w.g. 2jiu. rides. 
x4in.. 5/6; 8<7in.. 6/6; 11 3in.. 6/6; llx7in.. 7/6; 
3 - »:n.. 9/6: 14 - lliu.. 12/6; 15 • Mm.. 15/-. 
ALUMINIUM PANELS 18 B.w.g. 12 - 12in. 5/6; 14<9in. 
4/6: 12 ■ 8in. 3/6: 10 • 7in. 2/9; 8 ■ Oin. 2/-: 6 ■ 4in. 1/6. 



ALL PURPOSE TRANSISTOR PREAMPLIFIER 

Gain 14:1. 250 v. or 9v. input. Ready built with Mu Metal 
matching transformer lor Mikes. Pick-Ups. Tuners IE/ 
Instructions and circuit supplied. Post Free. • •»/ " 



THE INSTANT 

BULK TAPE 

ERASER AND 

RECORDING HEAD 

DEMAGNETISER 

Leaflet S.A.E. 
200/250 v. A.C. 




BAKER 12 in. STALWART 



The only Hi Fi Speaker 
available with choice 
of 3 or 15 ohm models. 
May be used with any 
Hi Fi or domestic 
sound equipment. 
Max. Power 15 watts 
Bass Res.. 40/50 cps. 
Flux.. 12.000 gauss. 

Voice Coil 1J in. 

Response, 45-13.000 
cps. 
Chassis Solid Alumin- 
ium, overall dia. 121 in. 
Overall depth 6 in 

Free 
ohm) 



[State 8 




CATALOdUE K.A.E. 
GROUP MODELS FOR VOCALS. 
BASS, LEAD and RHYTHM GUITARS 
30-10,000 ops. Voice Coils 15 ohms. Heavy Duty. 

Group 25' 'Group 35' 'Group 50' 
SS£ 5gns. SS£ tegns. ™£ 



tegns. «£ 18gns. 



LOUDSPEAKERS P.M. 3 OHMS. 2Jin.. 3in., 4in., 5in., 
7 in. -1m., 15/6 each; Sin. 22/6; 6}in. 18/6; lOin. 30/-; 
12in. 30/-; (15 ohms 35/-); 10inx6in. 30/-; 8in. *5in. 21/-. 
E.M.I. Double Cone 13: Sin.. 8 or 15 ohm models. 45/-. 
Stentorian lOin. HF1012,£5.10: 8in. HF812. £4.10; Crossover 
35/- ; Horn Tweeters 3-16 Ko/s. 10 w. 29/6 ; 20 w. 20 Ko/s. 99/8 
JACK SOCKETS Std. open-circuit 2/6. close circuit 4/6, 
Chrome Lead Socket 7/6. DIN 3-pin 1/3; Lead 3/6. 
Phono Plugs 1/-. Socket 1/-. Banana Plugs 1/-. Sockets 1/-. 
JACK PLUGS STANDARD. Chrome 3/-. DIN 3-pin 3/6. 
WAVE-CHANGE SWITCHES WITH LONG SPINDLES. 

2 p. 2-way. or 2 p. 8-way, or 3 p. 4-way. 3/6 each. 
1 p. 12-way or 4 p. 2-way. or 4 p. 3-way. 3/6 eaoh. 
Wavechange "MAKITS" 1 p. 12-way, 2 p. 8-way, 3 p. 4-way, 
4 p. 3-way, 6 p. 2-way. Prices include click spindles, ad- 
justable stops, spaces, etc., 1 water. 10/6: 2 wafer. 15/-; 

3 wafer. 19/6; 4 water. 24/-; 5 water, 23/6: extra waters. 4/6. 
TOGGLE SWITCHES, s.p. 2/-: d.p. 3/6; tLp.dt. 4/-. 



DE LUXE TAPE SPLICER. Cuts, trims, joins. lA/fi 
For editing and repairs. With 3 "piades. ,H I u 
4-CHANNEL TRANSISTOR MICROPHONE MIXER. 
Add musical highlights and sound eSects to recordings. 
Will mix microphone, records, tape and tuner RQ/R 
\v::h sepsrat? control; into sinde output «IJ/U 
2-WAY INTERCOM AND BABY SITTER. All transistor. 
2-way call buzzer. Desk or wall mounting. Good 
Volume. For home, office and shop. With RQ/fi 
long leads, battery, etc. >J J) u 

AM TUNER MEDIUM WAVE Three Transistor Snperhet. 
Ready built. Printed circuit. Ferrite aerial. 7 Q / R 

Size 5 } .31 ■ 1 j in. Ideal lor Tape Recorders. / a / «.■ 

3-WATT QUALITY AMPLIFIER I Transistor 7 c 1 
Push-pull. Ready bui.t. with volume control. ' »*/ * 

NEW Manufacturers' SURPLUS UHF BBC-2 AERIALS 

BBC-2 Double Gold Ring Set Top Model 23/8 

BBC-2 Five Element Loft Model 82/8 

BBC-2 Five Element Outdoor Wall Mounting 42/6 

* HAD 10 BOOKS * .Postage I'd. 

Radio. TV Valves. Diodes. Transistor equivalents 10/6 

High Fidelity Speaker Enclosures and Plans 5/- 

Transistor Snperhet Commercial Receivers 7/8 

Mullard Audio Amplifier Manual 8/6 

Radio Valve Guide, Books 1, 2, 3, 4 or 5 eaoh 5/- 

Practical Radio Inside Out 4/8 

Transistor Audio Amplifier Manual 3/8 

Shortwave Transistor Receivers 5/- 

Transistor Communication Sets 6/- 

International Radio Stations List 2/6 

Modern Transistor Circuits, for Beginners 7/6 

Sub-Miniature Transistor Receivers 6/- 

Wireless World Radio Valve Data 9/6 

At a glance Valve equivalents 67- 



rl/6 
< 1/9 
L2/- 



RESISTORS. Preferred values, 10 ohms to 10 meg. 
j w„ J w.. 20°„ 4d.; li w. 8d.; 2 w. 1/-; } w 10% 6d. 
HIGH STABILITY. I w. 1% 2/-. Preferred values. 
10 ohms to 10 meg. Ditto 5%, 10 ohms to 22 meg. 9d. 
5 watt i 0.5 to 8.2 ohm 3 w. 
10 watt S- WTRE-WOUND RESISTORS 
15 watt J 10 ohms to 6,800 ohms 
10K, 15K. 20K. 25K. 10W. 3/- 
MAINS DROPPERS. Midget. With sliders. 
0.3 a.. IK.. 0.2 a.. 1.2 K.. 0.15 a.. 1.5 K. 6/- eaoh. 
LINE CORD 100 ohms ft. twin plus resistance 1/- ft. 

WIRE-WOUND 3-WATT 1 WIRE-WOUND 4-WATT 
POTS. Miniature T.V. STANDARD SIZE POTS. 

Values 10 ohms to 30K, 3/3. LONG SPINDLE VALUES 
Carbon 30 K. to 2 meg., 3/- ! 50 OHMS to 100 K. 7/6 
VALVE HOLDERS. Int. Oct. Od. Mazda Oct. 6(L; B7G. 
B8A, B3G, B9A Moulded 9d. Ceramic 1/-. B7G, B9A cans 1/-, 
Valve base plugs B7G. B9A, Int. Oct. 2/3. 

C.R.T. BOOSTER TRANSFORMERS 

for heater cathode short or failing emission. 25% and 50" 
BOOST. 200/250v. A.C. input. STATE TUBE 
VOLTAGE REQUIRED. 2 or 6 or 13v. PRICE 



15/6 



BRAND NEW QUALITY 
EXTENSION LOUDSPEAKER 

In tough cream plastic cabinet with 20ft 
lead and adaptors. For any transistor radio 
intercom, mains radio, tape recorder, etc. 
3 to 15 ohm matching Oft / POST 
Size: 7! 5; 3in. <*U/" FREE 




RETURN OF POST DESPATCH Minimum P.P. Charge 1/6 un/ess otherwise stated. C.O.D. 51- extra. Full List //-. CALLERS WELCOME 

RADIO COMPONENTS SPECIALISTS 337 whitehorse road, west croydon 

Written guarantee with every purchase. (.Export — send remittance and eitra postage, no C.O.D.) (Buses 133.68 pass door). S.R. Stn. Selhurst. Tel. THO 1665 



775 



THE 

AMPLIFIER 

FOR 
CERAMIC 
PICKUPS 




222 STEREO AMPLIFIER 

There are a number of ceramic pickups capable of 
giving excellent results with a good amplifier. 
Our 222 was expressly designed for these pickups. 
It has all the other facilities you look for in a high 
fidelity amplifier and a choice of matching FM and 
AM-FM tuners 

£28 1 5.0 
£31. 9.0 
£25. 2.3 



222 STEREO AMPLIFIER 

223 AM-FM TUNER 

224 FM TUNER 
OPTIONAL CASE, teak and vinyl hide 
as illustrated. All models 

M5 STEREO RADIO DECODER 



£3.10.0 
£14.10.0 



For full details and technical specifications of all 
models, plus list of stockists, post coupon or write 
mentioning 1 PE/67. 

ARMSTRONG AUDIO LIMITED 

WARLTERS ROAD, LONDON, N.7 

Telephone: NORTH 3213 



% 



CbtMusfitortg 



name 

address 
2PW/67 



17in.— £11.10.0 

3 Star Guarantee 

-fcTube -frValves 

■^-Components 

Channels for all areas 

Carr. 30/- 



TWO-YEAR GUARANTEE 
EX-RENTAL TELEVISIONS 



FREE ILLUSTRATED LIST 
17"— 19"— 21 —23" 

WIDE RANGE OF MODELS 

SIZES AND PRICES 
DEMONSTRATIONS DAILY 




LATEST RADIOGRAM CABINETS £9.10.0 



Superbly made and styled 

in Veneered English 

Walnut 

Lift-up lid to changer and 
record storage compartment 

Position 8 x 5in. twin Speakers 

Dimensions: 40 x T6£ x 1 5Jin. 
Legs 1 gn. Carr. 30/- 

Other Models — Send for List 

RECORD PLAYER CABINETS 49/6. 
Latest designed covered cabinet-. 
Take? any modern Aatorhunger. 
P. & P. 7/6. 

TRANSISTOR CASES 19/6 9J s 61 X 
3Jin. P 4 P. 2/6. 

TV Turret Toners 2/6. New less 
valves- 81rm model* 6/-. Press button 
models 19/6. P. A P. 2/8 




TWO YEAR GUARANTEED 
TUBES 100% REGUNNED 

14ln.— 69/6 1 Tin.— 79/6 

21 in. * ALL SLIMLINE TUBES 
99/6 Carr. 10,6 

ADD 10 - OR OLD TUBE 



DUKE & CO. (LONDON) LTD. 

621/3 Romford Road, E.12 ILF 6001-2-3 



BUILD 



CIRCUITS 



YOUR 
on 

VEROBOARD 



— the Universal Wiring Board 



- J A 




obtainable from your local Retailer 

Retail enquiries to: 

NORMAN ROSE (ELECTRICAL) LTD. 

8 ST. CHAD'S PLACE, GRAYS INN ROAD, LONDON, W.C.1 

Technical enquiries to: 

VER0 ELECTRONICS LTD., Chandler's Ford, Hampshire 



Questions and Answers Series 

Q. &■ A. on TRANSISTORS 

Clement Brown 

Starting with the properties of semi-conductor materials, this 

book covers basic transistor circuits, transistors in radio 

receivers, high fidelity amplifiers and tape recorders and 

public address equipment. 96 pages. 60 line diagrams. 

Q. & A. on RADIO 

H. W. Hellyer 

Starting with the fundamentals of electricity and sound and 

radio waves, this manual provides a thorough grasp of the 

principles of radio and television transmission and reception, 

with emphasis on modern practical techniques. 

128 pages. 70 line diagrams. 

Only 8s. 6d. each from all booksellers or in case of difficulty 

by post, 10s. from Newnes. Tower House, Southampton Street. 

W.C.2 



776 



POWER SUPPLIES 



SECOND AND FINAL PART 



by H. T. Kitchen 



SEPARATE HEATER LINE 

There is a limit to the voltage that can be applied 
to the cathode of a valve when the heater is at 
chassis potential In the case of the series regulator 
valves, the cathodes will be several hundred volts 
above chassis potential, and any attempt to run the 
heaters of these valves from an earthed heater 
supply is doomed to failure as the heater to cathode 
insulation will break down, leading to premature, 
and possibly violent, valve failure. It is therefore 
customary to run the heaters of such valves from 
a separate heater winding, well insulated from 
chassis and all points having a PD differing from 
the cathode. If this separate winding is centre 
tapped it can be connected to the cathode of the 
regulator valve. If not, it can be left floating or 
one side connected to a potential divider across the 
h.t. supply so that the heater is at or near the same 
potential, above chassis, as the cathode of the 
regulator valve. The cathode of the error amplifier 
will be from 85V to possibly 100V, or fractionally 
higher, above earth potential, a figure that is within 
the heater cathode rating of most valves likely to be 
used in this position, so that a separate heater 
winding will not be required. 



E.H.T. SUPPLIES 

The high e.h.t. voltages required by many 
oscilloscopes cannot always be supplied by voltage 
multiplying circuits. For instance, a common e.h.t. 
value is 2kV, and a common h.t. transformer 
secondary voltage is 350V, so that a X6 voltage 
multiplier would be necessary. Higher e.h.t. and/or 
lower transformer voltages would require even more 
multiplying elements, an uneconomical situation 
both electrically and financially. Under these 
circumstances alternative methods have to be 
adopted. The use of a mains transformer having 
the requisite voltage output is one possibility, but 
such transformers are not only expensive but 
potentially dangerous, in more ways than one. 
Although the smoothing capacitors rarely exceed 
I/*F, they are capable of delivering a considerable 
amount of instantaneous power which is measured 
in joules, a joule being equal to i CV 2 where C is 
capacity in farads and V the voltage they are 
charged to. The initial shock would be severe 
enough, but unfortunately, in this context, the 
current delivered by the transformer is sufficiently 
high to speedily recharge the capacitors. Continued 
contact with such a supply would cause local 
burning of the flesh and possibly death. Considerable 
care must be exercised when dealing with such a 
supply, and it should be carefully discharged before 



being handled. The discharging of capacitors by 
means of a screwdriver should be avoided if at all 
possible, because the resulting bang is not good for 
people's nerves — and it certainly isn't good for the 
capacitor, as it is liable to fracture the dielectric. 
Instead, capacitors should be discharged by means 
of a resistor connected across them, values from a 
few kohms to a few hundred kohms being suitable. 
It is an excellent idea to fit high resistance bleeder 
resistors across all high voltage capacitors to 
automatically discharge them when the supply is 
disconnected. The working voltage — not current — 
of such resistors must be adequate. If in doubt, a 
number of series connected resistors could be used. 

R.F. HIGH VOLTAGE SUPPLIES 

The use of r.f. e.h.t. supplies have much in their 
favour, for although the voltage levels are 
comparable with transformer supplies, the current 
levels are very much lower. Although the initial 
shock will be as unpleasant as before, the r.f. 
oscillator will either cease working or, if it continues 
working, will do so at a much reduced efficiency. 
Continued contact with such a supply will therefore 
be far less hazardous than from a mains transformer 
supply. The r.f. supply will either consist of two 
valves, an oscillator and a power amplifier stage, or 
just one valve functioning as a self-oscillating power 
output stage, and this is the circuit shown in skeleton 
form in Fig. 11. The transformer for this consists 
of three coils, LI, L2, L3, which are usually wound 
on a Ferrox cube core. LI and L2 comprise the 
anode to grid feedback windings which cause the 
valve to oscillate, L3 is the e.h.t. winding. The 
inductance of LI in conjunction with CI determines 
the oscillator frequency. The number of turns of 
L2 and their spacing from LI determines the feed- 
back voltage which should not be excessive 
otherwise severe waveform deformation will occur' 
The number of turns for L3 determine the eht 
voltage. The operating frequency is a matter of 
compromise. The efficiency of the Ferrox cube 
transformer falls with decreasing frequency, whilst 
too high a frequency is liable to cause interference 
with nearby receivers. It is usual to choose a 
frequency in the 50kc/s to ,100kc/s range and to 
enclose the e.h.t. unit in a screened box with 
adequate decoupled h.t. and heater feeds. The valve 
must be a power type; EL84, EL34. 6L6 types being 
commonly used. 

The components in a power supply are amongst 
the hardest working of any and it is therefore 
essential to devote care when selecting these 
components and assembling them together. 

The smoothing capacitors are often electrolytics 



777 



because these offer a greatly increased capacity, size 
for size, than paper capacitors, which makes them 
an attractive proposition where space is restricted. 
In some other respects they are inferior to paper 
capacitors, particularly where polarity and internal 
noise level is concerned. Connecting an electrolytic 
with reversed polarity or across an AV supply is 
almost certain to end in the capacitors explosive 
destruction. The leakage current of electrolytic 
capacitors is appreciably greater than paper 
capacitors, but even worse, from some aspects, is 
that the leakage current is not constant, but varies 
sporadically — hence the "noisy" capacitor. This 
current also increases with increasing voltage across 
the capacitor, with the result that the DV output 
contains not only a percentage of mains ripple, but 
also a percentage of capacitor noise. Capacitors 
that have been stored for any length of time are 
apt to have a low internal resistance, and will pass 
excessive current, which causes overheating, if 
connected across a source of high DV potential. 
This excessive current 'overheating phenomenon is 
likely to be cumulative, culminating in another 
explosion. Such capacitors should be "formed" for 
a short while by connecting them to the DV 
potential via a moderate resistance of lOkfl or so. 
This resistor will limit the flow of current so that 
the capacitor cannot overheat due to passing 
excessive current. An interesting way of demonstrat- 
ing this would be to connect a high resistance 
(20kn/V) voltmeter across the capacitor and note 
the voltage across it on switching on, and then at 
fairly frequent intervals. At first the capacitor 
would pass a fairly heavy current (this could also 
be monitored by connecting a milliameter in series 
with the capacitor) and the voltage would be low. 
As the capacitor was "formed", its current leakage 
would decrease, and the voltage would increase, 
until a state was reached when the voltage and/or 
current remained constant. At this stage the 
capacitor could be considered to be fully formed. 
The practice of using an expensive multimeter to 
measure leakage current directly is fraught with 
danger, because should the capacitor suddenly go 
s/c or pass an excessive leakage current, the chances 
are that the meter movement will suffer. 



WATCH THE CAPACITOR RIPPLE 
RATING 

One aspect of capacitors that is often overlooked 
is that in the process of smoothing the pulsating or 
raw DV from the rectifier, they have to pass what 
may easily be an appreciable AV current. Jn this 
respect, the reservoir capacitor, i.e. the capacitor 
following the rectifier, has to pass the greatest 
current, and the smoothing capacitor, i.e., the 
capacitor on the load side of the smoothing choke 
or resistor, the least current. This can be easily 
visualised if one remembers that the unwanted 
ripple voltage has to be "lost" somehow, and the 
only way of doing this is to short circuit it to earth 
via the reservoir and smoothing capacitors. These 
components must therefore possess an adequate a.c. 
ripple rating which will be greater than the mean 
DV current by a factor of >J2. 




Fig. 1 1: Transistor and valve e.h.t. oscillators. 

In the part of the article dealing with stabilised 
power supplies it was stated that the series regulator 
valve could consist of several valves in parallel if 
the current capacity of a single valve was inadequate. 
This, of course, is perfectly true, but needs a little 
further elaboration. Since the combined slope of a 
number of valves in parallel is the sum of the 
individual valves' slopes, the chances of instability 
increase with every additional valve. Generous use 
of grid stoppers around lkil to lOkii plus anode and 
screen stoppers at 10ft and 100ft or thereabouts 
respectively would minimise the chances of 
instability. It is essential that these stoppers are 
wired as close to their respective pins as possible. 

SITING COMPONENTS 

The positioning of components on a chassis must 
also be considered. Rectifiers in common with 
other valves have an aversion to being in a strong 
magnetic field and should therefore be positioned 
as far from the mains transformer as is practicable. 
Failing this they should be positioned where the 
magnetic field is least, i.e. at right angles to the 
core. Wherever possible other inductors should be 
positioned with their cores at right angles so that 
mutual coupling is at a minimum. 

Finally, we come to heat, and lots of it, too, for 



IH.T.+ 250V 




10 15 20 25 30 35 40 45 50 55 60 

Time (minutes) 

Fig. 12: Simple method showing how to measure leakage 
current and voltage. 

much of the energy in a power pack is dissipated 
as heat. If the power pack is to give long and 
trouble free service, adequate ventilation is 
absolutely essential. Without it, all the care taken 
in the choice of components, and in their integration 
as a working whole, will be set at naught. ■ 



778 



STUPENDOUS OFFER— £11 for £2 HEAT AND LIGHT UNIT 




ntly sold 
1 r tl" 19.fi. Note 
ill-. i- features: 

• LoU£ & Medium 

W m • Long 
dial • Push pull 
output • A.V.C. 
and feed back 

• Kerrite aerial 

• Six transistors 

• Cabinet size 
MB. x 3in. x 
liiu. with carry- 
ing -t rap. You get 

evervihlng vou need and instruction* 39/6 plus 
r: •: P. a P. Battery 1/9 extra. Data separately 2/6. 

PP3 Eliminator — play your pocket i 
radio from the mains: Save £'s. 
Complete component kit comprises 4 
rectifiers — mains ilropper fegtotWIPCBi 
smoothing condenser and iu-ti net ions. 
Only 6/6 + 1.'- post. 

HI-FI SPEAKER BARGAIN 

l'.'in. High fidelity 
I iu l-peaker. High 
flux permanent 

magnet type with 
either 3 or 15 ohm 
speech coil. Will 



idle up m 



10 



Brand 
nous maki 

89/6 with 
. tweeter 35/- pi 





3/*5 post and insurance. 

2ikWFAN HEATER 

3 heat positions to suit 
changes in weather: lkW, 
llkW and .'.ikW: also 
blows cold tor summer. 
has therm »tatic safety 
cut out "Proper" price 
£5.17.11. Tours lor only 
£3.15.0. Plu- •,(! post 
and insurance. 

MAINS TRANSFORMER. Upright mi.unting with 
primal v tapped 280, 2-20. 240 v. H.T. -econdary 
i- Jiii-ii-250 v. at 100 mA. and it has two L.T. 
secondaries of 6.3 v. 1J amp. — unused (removed 
Tr..iii -inlpment), 15/- plus 3/6 po-l and insurance. 
•■C"' CORE POTTED OUTPUT TRANSFORMER. 
Made by the famous •'Pamieko" company these 
are the best money can buy, we can offer a bargain 
15 watt rating, centre tapped primary with 
y for 3 ohm speaker. Potted and in black 
Move enamelled case ior upright :n -Hinting these 
will make your amplifier or rig look perit-i t at only 
12/6 plus 3/6 carriage and insurance — hurry ior 
the-e. 

i MEG. POTS. By Erie, standard Jin. spindle. 1 In. 
Ion*. 7d. each in doz. lots, otherwise lOd. 
! MEG. POTS WITH D.P. SWITCH. Again by 
Brie. Standard size spindle lin. leneth. lOd. each 
in dor- lots, otherwise 1/3 each. 
MINIATURE PICK-UP. For pop record-— tub is 
in;, It- by Cosrnocord — has a crystal cartridge and 
toag play sapphire stylus — offered for less thau the 

de price of the stylus only — namely 3/9 
each or 36/- doz. 

MINIATURE RELAYS with removable covers. 
\.-r\ -en-it ive twill close on only 20 mA). Coil 
resistance 10,000 ohms — contact- are three sets: 

■ i for change over pair to open circuit 
and the third pair to close circuit — perfect order 
Bnnsed (removed from equipment). 7/6 each. 
CAR CHARGER OUTFIT 3 amp. trau-iormer 
and -i-lenitim full wave rectifier only 27/6 plus 

FLUORESCENT LIGHT BITS. Comprising choke, 
lampholdcrs, starter and two chrome tube clips. 
2" n't 19/6. 40 watt 11/6. SO watt 17/6. "15 watt 
19/6 plus 4/6 p. it p. 



SEM 


-CONDU 


STOR BARGAINS 


I,,,,,- 




Type 






T'jpe 




No, 


Price 


No. 


Price 


No. 


Price 




15/- 


MAT101 


8/6 


0(71 


4/- 


8N1728 


10/- 


MAT120 


7/9 


OC72 


51- 






MAT121 


8/6 


OC.5 


6/- 


2X1747 




OA5 


5/- 


OC7H 


5/- 


2M7-IS 


10/- 


OA10 


6/- 


OC77 


'?/- 






OA47 


3/- 


OC7S 


51- 


A' 27 


»/- 


OA70 


2/- 


OCT SO 


51- 






OA79 


2/6 


OC81 


5/- 


A' Vis 


5/6 


OASt 


2/6 


Of.'SID 


5/- 


ACV19 


6/6 


OA-j 


3/- 


OC82 


5.'- 


AIVJO 


5/6 


OA9I) 


2/6 


OCS3 


5/- 


Al V-'l 


6/- 


OA91 


2/6 


OCJU 


6/- 


AIV22 




OA200 


3/3 


OC139 


8/6 


AI114 




OA202 


4/3 


OC140 


12/8 


AF115 


6/6 


OC22 


10/- 


OC170 


5/- 


■ II 16 


7/- 


OC23 


17/6 


Of'171 


6/- 


All IT 


51- 


OC24 


22/6 


OC200 


»/- 


Al.l- 


12/6 


OC26 


7/6 


OC201 


12/6 


At 139 


17/6 


OC28 


15/- 


OC202 


13/6 


A 1 1 "'I 


19/6 


OC29 


17/6 


OC203 


12/6 


AKZ12 




OC35 


13/6 


OCP71 


19/8 


AS/21 


15/- 


OC36 


15/- 


OBP12 


8/6 


BCI07 


14/8 


OC42 


6/8 


ORPUi.l 


51- 


BY 100 


5/6 


OC44 


6/- 


SB07s 


6/6 


BYKI3 


7/8 


OC45 


4/- 


SB305 


8/6 


S1AT1U0 


7/9 


OC70 




4/- 


SB231 


IU/- 



The above is a list of the more popular types in 
-- ■- k —we can also supply almo-t every semi- 
induct T made — please send 1/6 lor couiprchen- 
- 1 and equivalent data. 




Bring luxury to your l-athr«im — have 

comforting heat where you now . . i , 1 -. haw 

light— all the parts to build a full size 1 Irtln. 

diameter) model are now available — you 

will build it in an hour — 12in. T.'iii mil 

circular silica gla-s enca-ed elenieut — opa; 

bowl for up to 100 wutt lamp— non-rust 

spun reflector— white enamelled base heat shield pull 

magnificent unit as sold normally al S4.5.0 only 49/6 plus 7,6 

carr. and Insurance. 

SUPERTONE G.C.V. 

Saves you work- 
It's partly built 

Like Its predecessors this lati-t Com- 
panion has full B performance— such 
as only a good wooden cabinet and 
liiflu.v speaker can give, aud due to 
it- heing parlly built you will have 
it going In an evening. Note theae 
feat tires: 

• All Milliard Transistor- including 
3x AF1I7. 

• Two-tone Cabinet, size 1 1 x S x Bm- 

• All circuit requirement* — I'u-h-piill 
output -A.V.C. and feed back, ale. 

• Printed circuit board all wired only i 
w.c. Switch and Tuning Condenser, 

• Prc-aligned IF stages complete with full ln-l ructions. Price only £8.19.1 
plus 0/6 post and insurance. 




THIS MONTH'S SNIP 



leek 

£7. 



T!u- month's snip is tl'. 
Garrard model 3000 oampleta 
•rttfe ■ ■■•ramie cartridge. The 
out-tan, ling feature of thi- 
reconl player is Its low nin> 
no which facilitates exotUetll 
tracking characteristics and reduces 
raontd wear to the minimum. Size 
13 7 ,,,ln. wldexllj in. front to rear 
clearance. 4" „ln.above and 2j in. b— 
Supplied complete with template if required and sen:. 
1.6. plus 7 6d. carriage and Insuranre. 




INFRA-RED 
HEATERS 

Make up one of these latest type heaters, i 

bathroom, etc. They are simple to make from our t, 

easy-to-follow Instruction, o ilica enclosed 

elements designed for the oorreci infra-red wavelength U microns), 
for 750 watts element, all parts, metal caatnf a- lllu-trai.-.i 21/6. Ml 
post and Insurance. Pull switch 3 - extra. 

F.M. TUNER 

of exceptional quality. giving really 
rantastk results with virtually no noise, 
Suitable for mains or battery operation. 
6 transistors— three IK t m •- looMe 
UssfttntDBtor. i oiii'l'i". new. and 
built up all readv to work on cha-si-. 
Size 6in. x 4in. x 2ln. with tuning scale 
and -dow tuntiou drive. A £12.12.0 lOAttf 
for only £8.10 0. 

NOW INSTANT START 

CIRCULAR FLUORESCENT 

Bring* -im- hine int., your home. 150 watt- 

of light but uses only 40 w. Beautiful 

fittings with glass, non-p!a-tic Centre, 

i .1 -(.nt tube and choke conirol. 

Made DI Philips. Regular price t'4.i:..ii. 

Bpeetal budgel price 85/-, phu 8 1 

c. and In-. PleaM state colour of glass 
centre, white, pink, blue, red, black, 
yellow or cream. Also whether 
iitlng model. 80 watt model 99/6. 





plod into lamp holde 



eluni 



3M SCOTCH TAPE 



nd gnaranti 

ormal rpooh 

1500ft. 

90Oft. 

l,200fl 



•d perteet and not second in anyway — a 



9/- 
11/6 
16/- 



Long Play 



Sin. 90uft. 11/6 

Slin, 1,200ft. 16/- 

7ln. 1,800ft. 23/- 



Brand new, unused 
connoisseurs tape on 
Standard Play Dm. 

5 (in. 

7in. 
£3 post free otherwise add 2'- post and Insur 

MAINS TRANSISTOR POWER PACK 

Designed to operate transistor -els and amplifiers. Adjustable output <1 v. B v. 
12 volts for up to 500 mA "la-- I! working). Take- the place of any of the 
follow. iu; balletic.-: I'PI. PP.'i. PP4, PP»J, PF7i Pr"- 1 - and ..Ih.r-. hit .ompriscs: 
miiii- traostc^mer-rcetloer, BnootUng and load reatatar, 6,000 aud . 
eondensers, Zener diode and butrrjoUons. Kial-nlpatonly 14/6. plus it t post. 

BATTERY CHARGER — FREE 

9v. SlckelCadmium Batt.iy : yp,- PP:i tilts all popular poekel tran-i-tnn..) ran 
I" r.-chirtjrtl son /,„,,. Price wilh tmn-lortner type battery charger, only 
87/-, p. 4 i. Si-. Chargeable replacements also In stock for VI 18/6; I' 12 38/-. 



mrAA-ftEo f 



SENSITIVE LAV 



a 



FLUOOESCENT 
SCDEEN 



VIE WING WIHQQW 



SNIPERSCOPE 

Famous war-time 
"cat's eye" used 
for seeing in the 
dark this is an 
infra-red image 
convener Hep 

with a silver 
cae-iuui screen 
which lights up 
(like a cathode 
ray tnbe) when 
the electrons re- 
leased by I he 
infra-red strike it. 
opportunity for some interesting experi- 

ments. 5/- each, post 2 .-. Dale will be supplied 

with .-ells, if requested. 

FLUORESCENT SNIP 

Your ooportunity to install non-lllcker strip 
lighting at slllv price— this month we offer the 
famous A.E.I. (Mazda) instant start lighting 
t nun-former suitable for one 4ft. 40 watt tube. 
This transformer is listed at over £7 but this 
month you can buy the complete kit comprising 
instant start choke/transformer, two tube ends 
and two Terry clips to hold tube. Special snip 
price only 14/6, plus 4 6 post and insurance — don't 
BUSS this tremendous bargain. 

TUBULAR HEATERS 

Xew and unused made by CJ.E.C. rated at 00 
watt- per ft.— these are ideal in airing cupboards, 
I, '.•■ 1 1 ""iii-.othces, stores, greenhouses, etc.. curtains 
or papers can touch them without fear of scorching 
or fire. Supplied complete w-ith fixing brackets ami 
available in the following sizes. Prices which are 
about 1 of list price includes carriage by B.R.S. 
sit. 30/-; 10ft. 36/-: 12ft. 48/-. 
Also in twin assemblies (one pipe above the other) 
4it. 40/-: 3ft. 46/-; Bit. 52/-. 

THERMOSTATS 

Type "A" 15 amp. for controlling room heaters, 
greenboase, airing cupboard. Has spindle for 
pointer knob quickly adjnstableirnm30-s0°l-.. 9/8, 
plu- 1 - post. Suitable box for wall mounting, 5/-. 
P. ft P. 1 -. 

Type "B" 15 amp. This is a 17m. long rod type 
made by the famous Sunvic Co. 8pmdle adjusts 
this irom50-aoO°P. Internal screwalters Ihesottmg 
so this could be adjustable over 30 c to 100fl°F. 
Suitable for controlling furnace, oven kiln, ininier- 
-i m heater or to make flame-start or fire alarm. 
8/8 plu-- 2 '8 post and insurance. 
Type "D". We call this the Ice-stat as It cuts in and 
out at around freezing point. 2.'3 amps. Has many 
uses, one of which would be to keep the loft pipes 
from freezing, il a length of our blanket wire (16 
yd-. 10/-) is wound round the pipes, 7/6. P. * P- 1/1, 
Type "E". This is standard refrigerator themo- 
stal. Spindle adjustments cover normal refrigerator 

temperatures. 7/6. plus 1:'- post. 
Type "F". Glass encased for controlling the- temp. 
of liquid — particularly those in glass tanks, %-ats 
■ •r sinks — thermostat is held (half submerged) by 
rubber sucker or wire clip— ideal for fish tanks — 
developers and chemical baths of all types. 
Adjustable over range 50° to 150°F. Price 18/-, 
pin- 2<- post and insurance. 

750mW TRANSISTOR AMPLIFIER 

-^^ J&3& •* transis- 

"■■^k- tors includ- 

push-pull 
Input for 
[ crystal or 
L magnetic 
S microphone 
*&or pick-up 
W — feed back 
I loops— sen - 
j aitivity S 



itlyif 



Post and insurance 2,'G. Speakers J 
13/6; '5x4 ir.. 14/6. 

PHOTO ELECTRIC KIT 

All parts to make light operated switch /burglar 
alarm Counter, etc. Kit comprises printed circuit. 
Laminated Boards and chemicals, Latching relay. 
Infra-red sensitive Photocell and Hood. 2 Tran- 
sistors, coud., Terminal block. Plastic case. Esscn- 
t ial data, circuits and P.C. chassis plana of 10 photo 
electric devices including auto, car parking light, 
modulated light alarm. Simple Invisible ray 
switch — counter — stray light alarm— warbling 
tone electronic alarm — projector lamp stabiliser, 
etc, etc. Only 39/6 plus 2/- post, and insurance. 

MULTIPURPOSE NEON TEST UNIT 

Robust, nsefnl and instructive — test Insulation 
— capacity — continuity — resistor — volume 
controls — ai-ti acts as signal injector and L-T. 
fault tinder— kit comprises neon indicator, 
4 way wafer switch, ebonite tubes, resistors. 
.-. terminals, etc., with diag. only 
9f6 pfcn B - post and insurance. 



Where postage is not definitely stated as an 
<-xtra then orders over £8 are poet tree. 
Bekxw £3 add 2/9. 



ELECTRONICS (CROYDON) LIMITED 

(Dept. P. W.) 102/3 TAMWORTH RD.. CROYDON, SURREY (0pp. W. Croydon Stn.J 
also at 266 LONDON ROAD, CROYDON, SURREY 



779 



BRAND NEW AM FM (V.H.F.) RADIOGRAM CHASSIS 
AT £15.15.0 (Carriage Paid) 




Chassis size 15 x 6j x 8} in. high. New manufaetxire. Dial 141 x 4in. In 2 colours; 

predominantly cream. 200-250V. A.C. only. 

Plck-np Ext. Speaker. Ae. f E. and Dipole Sockets. Five push-buttons — LW, MW, 

8W, FM and Gram. Aligned and tested. O.P. Transformer Tone control 1000-1U00M; 

200-550M; 88-98 Mc/s, 6-17 Mc/s. EZ80 rect.; ECH81 EF89 EABC80 EL84. ECC85, 

3-ohm speaker required. 

9 x 6in. ELLIPTICAL SPEAKER, 20/- to purchasers of this chassis. 

TERMS: (Chassis). £5.5.0 down and 5 monihlv payments of £2.6.0. Total H.P. 

price, £16.10.0. Cheap Room Dipole for V.H.F., 12/6. Feeder 6d. per yard. Circuit 

diagram 2/6. Carriage to N. Ireland, 20/- extra. 



NEW 6 PUSH-BUTTON STEREOGRAM CHASSIS. M.W.: S.W.I; 8.W.2; V.H.F., 
Gram; Stereo Gram. Two separate channels for Stereogram with balance control. 
Also operates with two speakers on Radio. Chassis size: 15 x 7 x fljin. high. Dial 
cream and red. IS x 3in. 190-550M; 18-8IM; 60-187M; VHF 86-100 Mc/s. Valves: 
ECC86. ECH81, EF89, 2 x ECL86, EMS4 and Rert. Price £19.19.0, can-, paid 
or £6.13.0 deposit and 5 monthly payments of 66/6. Total H.P. price £20.15.6. 
Cream moulded escutcheon included. 



TAPE AMPLIFIER FOR MAGNAVOX 
TAPE DECKS — 2 or 4 TRACK (4 TRACK 25/- EXTRA) 

Chassis 12] x 51 x 4'in. high. Plastic front panel "gold" Uulsh — 12J x 4]in. 200-280 
A.C. Record/Playback amp. switch; Off/On-Tone: Vol/Mic; Vol/Gram; Mic. Input; 
Gram. Input; Monitor; Speaker Socket*. Valves 6BR7; 12AX7: EM84; EL84; 6X4 
Separate power pack. Complete amp. and power pack, £10.17.6. (6/- P. * P.). Re .vine 
covered cabinet (tan) 15i x 17 x 9] in. high with sloping front for amp; complete 
with two tweeter speakers, and special adapting bracket- for Magnavox Deck — 
85/- (8/- carr.) 3 speed Magnavox 2 track tape deck £10.17.6: 4- track £12.15.0. 
Complete Recorders (with speed compensation) 2-track £29; 4- track £32 (carr. 25/-). 
Worth £10 more on normal retail prices. 



SUPER 6 

LONG a MEDIUM WAVE 
TRANSISTOR RADIO 




A quality radio available as a kit or ready-built. The sparkling perfo.. 
superb finish of the completed receiver give yon value equivalent to 
commercial model. 

•*• All new parts, -fa 6 transistors and diode. ■*■ 350mW output. -jc Superhet circuit 
■A- Fcrrltc rod aerial, jr Weymouth Radio printed circuit board, -fc Component 
positions and references printed on back of board. + Nicely styled wooden cabinet 
11 x 7i x 3]ln. -4r Vinyl covered in various colours. -A- 6 x 4in. "speaker giving good 
bass and treble response. -fr Full instruction booklet, 2/-. Free with kit. -4- T.f. 
frequency 470 kc/s. * Lining up service If required. •*- All parts supplied separately. 
Write for list, 8.A.E. COMPLETE KIT ONLY £>A n A 



OR FULLY BUILT £6.7.6. 



: arid Carr. Paid. 



TRANSISTORS AND DIODES 

OC2I1, 7/8; OC44 3/6; OC46 8/6; OC71, 3/-; OC72, 4/-; OC81, 3/8: OC81D, 3/6; 
OC82, 6/-; OC83, 3/8; OC1B9, 8/-; OC170, 7/-; OC171, 8/-; OC172, 8/6; AC127, 7/6- 
AF115,8/8;AFllfi.8/-;AF117.5/-;AFllS, 7/6;AF119, 7/6;WG4B, 9d.; OAS1, 2/6; 
OA79, 2/8; OA80, 2/6; BY100, 4/-. Part 4d. any quantity. 

STEREO-AMPLIFIER 2x4 WATT 

Valves ECC83, 2 x EL84, on printed circuit approx. 4 x 41n. Neg. feed back. Controls 
(vol. or tone) on separate panel, 6J x 2in. Separate power pack with rect., double 
wotmil mains trans., connection socket, etc. Supplied fully wired and tested with two 
O.P. transformers for 3-ohm speakers, only £4.15.0 (7/6 P. & P.). Two speakers, 8in., 
3-ohm for 20/- each, post paid. If ordered with above Amp. 

BATTERY ELIMINTOR. BJ x 4} x 2Jin. for 90 v. H.T. at 20mA and 1.3 V. at op 
to 280mA. Fully built, 55/- carriage paid. 

GLADSTONE RADIO 

66 ELMS ROAD, ALDERSHOT, Hants. 

(2 niiii-. from Station and Buses) Aldershot 2* > >40 

CLOSED WEDXE8DAY AFTERNOON 

CATALOGUE 6d. 

Bulk enquiries invited for Export. 



■**»»%» %.. 



TV TUBES 

REBUILT b RESCREENED 



SUFFOLK TUBES LTD, 

1/3 Upper Richmond Road 
Putney, London, S.W.15 
Tel.: Vandyke 4304/5267 



by Britain's largest 
independent Tube 
Rebuilder 



MIDLAND TUBES LTD. 

467/483 Oldham Road 
Manchester, TO 
Tel.: Col lyhurst 4412 




LOW COST BABY ALARM, USTF.R- 
COM. RELAX AND SAVE YOUR 
LEGS OUR SPECIAL PRICE 54/6d.— 
BATTERY INCLUDED— usually 7 gns. 
Fitted in seconds ! ! Despatch by return. 



2 Station System ideal for 
Home, Office, Sick room — 
endless uses. Operates on 
one 9 volt battery with a life 
of 4 to 6 months. Two fully 
transistorised sets — either 
one can speak or listen to the 
other even if switch is at 
"off" position. Size of both 
master and sub station 

3 x 2 x 4in. Two tone strong 
plastic cases finished with 
silver trim. Complete with 
66 ft. connecting cable and 
fitted jack-plugs, staples and 
fixing tape, battery and 
instructions. Postage, pack- 
ing and transit insurance 3/-. 



VALVES 



SAME DAY SERVICE 

NEW! TESTED! GUARANTEED! 



CETC 1R6, 185. 1T4, 3S4. 


3V4, DAF93 


, DF91, DK91, DL92, DL94. 




■ «* Set of 4 for 18/-. DAF96, DF96, DK96, DL96, 4 for 24/6 




7/6 


10C2 11/6 


DF96 


6/- EF89 


5/- 


PENA4 


fi/9 


UCH81 6/- 


H5UT 


7/3 


10F1 9/9 


DH76 


8/6 


EF91 


8/8 


PEN36C15/- 


UCL82 7/- 




7/9 


10P13 8/6 


DH77 


U- 


EF92 


2/3 


PEN383 9/6 


VCLS3 8/! 




4/» 


12AT7 3/9 


DH81 


;2/>. 


EF97 


7/6 


PFL20014/- 


UF41 8/- 






12AUI1 4/8 


DK32 


:/a 


EF183 


K/H 


PL36 


8/H 


UF80 11- 




8/» 


12ATJ7 4/9 


DK91 


W 


EF184 


«/- 


PL81 


6/9 


CF89 5/£ 






12AX7 4/9 


DK92 


«/■ 


EL33 


«/« 


PL82 


H/K 


UL41 8/£ 


3A0 


7/- 


13K7GT 3/6 


DK96 


Hid 


EL38 


ii/a 


PLS3 


«/- 


CL44 15/- 




h/ti 


12K8GT 7/9 


DL33 


m 


EL41 




Pl-54 


H/3 


UL84 5/£ 


3S4 


4/9 


12Q7GT 3/6 


DL35 


5/- 


EL42 


7/9 


PL500 


18/H 


UY21 8/£ 




ft/6 


20F2 10/6 


DL92 


4/9 


EL84 




PL801 


7/H 


CY41 4/t 




4/B 


20L1 14/- 


DL94 


h/K 


EL90 




PX25 


7/9 


UY85 4/t 


SV4G 


7/9 


20P1 9/- 


DL96 


«/- 


EL95 


M- 


PY31 


H/H 


VP4B 11/- 


iYSGT 4/11 


20P3 9/- 


DY86 


H/H 


EM80 




PY32 


8/H 


VP1321 21/- 






20P4 13/6 


DY87 


H/K 


EM81 


.73 


PY33 


8/H 


W76 8/( 




H/8 


25U4GT11/6 


EABC80 6/- 


EM84 


ft/0 


PY80 


h/8 


W77 2/1 








EAF42 


7/H 


EM87 


K/ti 


PY81 


h/;i 


Z77 3/1 






S0C17 11/6 


EB41 


4/- 


EY51 


H/!i 


PY82 


b/- 


Transistors 




4/9 


80C18 8/- 


EB91 


2/8 


EY86 


6/- 


PY83 


b/9 


AC107 10/- 




4/- 


30F6 9/9 


EBC33 


67- 


EZ40 




PY88 


7/3 


AC127 7/( 






80FL1 10/6 


EBC41 


m 


EZ41 


H/H 


PY800 


H/K 


AD140 15/( 


1BB6 


4/8 


SOLI 5 11/- 


EBF80 


«/- 


EZ80 


3/D 


PY801 


6/6 


AF102 18/- 






30L17 12/- 


EBF89 


h/H 


EZ81 


4/- 


R19 


7/6 


AF115 6/( 








ECC81 


8/9 


GZ32 


9/- 


R20 


.12/11 


AF116 B/( 




7/H 


30P12 9/9 


ECC82 


4/9 


KT61 


6/6 


U25 


a/- 


AF117 5/- 








ECC83 


;/- 


N18 


h/K 


U26 


8/9 


AF11S 13/t 


1F14 


9/- 


30PL1 12/9 


ECC84 


m 


NTS 


14/9 


U47 


8/H 


AF124 9/- 


JF23 


H/M 


30PL1311/9 


B0085 


5/6 


PC97 


K/H 


U49 


9/6 


AF125 8/f 


)K7G 




35L6GT 6/8 


ECF80 


j/« 


PCC84 


h/« 


062 


4/6 


AF126 8/- 






35W4 4/6 


ECF82 


h/h 


PCC89 


H/H 


D78 


H/H 


AF127 8/- 








ECP86 


w- 


PCC18S 


»/- 


U191 


10/6 


OC22 17/t 


(148 




85A2 5/9 


ECH35 


K/- 


PCF80 


6/6 


TJ301 


ll/H 


OC25 9/f 






1S5BT 20/- 


ECH42 


W- 


PCFS2 


6/- 


U801 


IK/3 


OC26 6/1 






(!003 12/6 


ECH81 


67- 


PCFSfi 


H/H 


UABC80 5/9 


OC44 4/! 


OVfitiT 


H/H 


AZ31 8/9 


BOH84 


8/H 


PCFS00 10/6 


DAF42 


7/9 


OC45 3/! 


1X4 


H/H 


B36 4/6 


ECL80 


W- 


PCF80I 




TJBC41 


B/W 


OC71 3/( 








ECL82 


«/8 


PCF802 


H/K 


UBF80 


H/- 


OC72 4/1 


7B6 


10/9 


DAC32 7/3 


ECLS6 


w 


PCF803 


8/- 


UBFSS 


5/9 


OC75 5/i 






DAF91 8/9 


EF39 


'.'.IV 


PCL82 


K/H 


UBL21 


9/- 


OCS1 3/( 


7C5 


»/« 


DAF96 6/- 


EF41 


m 


PCLS3 


8/6 


CCC85 


B/6 


OC81D 3/1 








EF80 


w 


PCLS4 


7/8 


UCF80 


8/3 


OC82 5/1 








EF85 


bl- 


PCL85 


8/3 


TJCH21 


w 


OC82D 5/1 


7Y4 


5/- 


DF91 2/9 


EF86 


k/s 


PCLS6 


8/6 


CCH42 


8/9 OC170 5/1 



READERS RADIO 



85 TORQUAY GARDENS, REDBRIDGE, 
ILFORD, ESSEX. CRE 7441 

Postage on 1 valve 9d. extra. On 2 valves or more, postage 6U. per 
valve extra. Any Parcel Insured against Damage in Transit Hd. extra. 



780 



CLUB 
SPOT 



FAREHAM & DISTRICT 3 
No. 14 AMATEUR RADIO V 

CLUB E 



FAREHAMS radio club was formed, like so 
many others, by two or three amateurs meet- 
ing informally and "chewing the rag". Just two 
years ago an inaugural meeting was arranged and 
well over a dozen potential members crammed 
into the lounge of the first elected Secretary's QTH. 
From this encouraging response it was obvious that 
there was sufficient local interest to put things on 
a proper basis and so the Club was born. 

Just one week later saw the first activity in the 
form of a world wide contest for which a station 
was set up on the stage of a disused school hall. 
This venture, apart from being the first introduc- 
tion to "ham radio'* for several members, was 
nearly a full scale disaster. Hooligans tore down 
the antenna, the weather was bitterly cold and the 
mains power supply all but melted. Far from being 
disheartening, the experience cemented all those 
who froze through the night into a club with spirit. 

The first problem was that of accommodation 
and it was decided to hold monthly meetings in 
the back room of one of the local hostelries. With 
an equal membership of licensed amateurs and 
SWL's the pattern of these enjoyable evenings was 
soon established with slow morse for beginners, 
talks by the older hands on some of the mysteries, 
or perhaps a demonstration of someone's latest 
acquisition, followed by the inevitable natter over 
a "jar". 

The Sunday morning net helped a good deal in 
the early days to catch many SWL's and others so 
that within a few short months the membership 
exceeded thirty. Biggest trouble was the provision 





The club station in action. Left to right — G3VEL, G3TZM, 
and SWL Jack. 



Club President G2QK directs operations. Left to right— 

G3PMM. G3VFI, Junior Op, G3VLY. G3TZM, G3VOR 

SWL Brian. 

of transmitting facilities and more suitable accom- 
modation was sought by the Club's President. 

After much negotiation and effort the club found 
its permanent QTH at the Portchester Community 
Association. This meant a move away from the 
town centre and it was decided to change the 
Club's name to one more in keeping with the new 
circumstances. Meetings were now held every Sun- 
day and before long such was the demand that 
an additional evening for practical work was 
arranged. Once again members rallied to the cause 
and workshop facilities were obtained together with 
an adequate supply of the usual tools. 

Sundays are now set aside for more organised 
activities and a full and varied winter programme 
is under way. This takes the form of a monthly 
lecture or demonstration, the remaining evenings 
being reserved for discussions, informal" talks and 
quizzes. 

Memorable occasion recently was when a new 
call-sign broke into the Sunday morning net. The 
newcomer turned out to be not only a club member 
but the Chairman himself. 

Regular features in the club calendar are the 
Fareham Fair and the local Gymkhana. These give 
club members the opportunity to set up a tempor- 
ary station, younger members looking after the usual 
tree climbing. 

The Club now has a membership of over 40 with 
16 licences, interests ranging from Top Band DX 
to the technicalities of u.h.f. Now with its own 
AR88D, a respectable antenna system almost com- 
pleted and a newly acquired all band transmitter, 
the club is well and truly "on the air". 



781 



E TAPE RECORDING YEARBOOK— 1966 

= Published by Print and Press Services Ltd. 

= 128 pages, 9 x SJIn. paperback. Price 7s. 6d. 

FOR those who, like the reviewer, spend their 
working days immersed in the technicalities of 
tape recording, this annual collection of facts 
and figures is an indispensable reference. The cur- 
rent issue is no simple reprint, but has been 
brought as nearly up-to-date as publication times 
allow, thus providing current information on tape 
recorders, decks, mixers, microphones, radio tuners 
and miscellaneous accessories. In addition, the 
important section on manufacturers and agents has 
been revised and is a directory of real value. 

For the ordinary enthusiast, the Yearbook offers 
comprehensive data on many different machines, 
plus articles of interest by well-known writers in 
this field dealing with recording, using microphones 
and tape-plus-cine respectively. 

The catalogue section follows the same form as 
in previous years. The only omission we would 
like to see rectified is the input and output 
impedance and sensitivity specification — but, after 
all, for 7s. 6d., one cannot expect everything. As 
it is, we certainly get our money's worth. — HWH. 



= TAPE RECORDERS— HOW THEY WORK 

= By Charles G. Westcott and Richard F. Dubbe 

= Published by Foulsham-Sams Technical Books Ltd. 

= 177 pages, 8} x 5}ln., hard covers. Price 24s. 

SLIMMER, neater, and two shillings cheaper, 
this is the latest edition of the successful 
volume reviewed in the September 1965 
issue of Practical Wireless. 

To achieve the fining down, the publishers have 
used a cleaner type, omitted the final chapter on 
Special Applications, and small parts of other 
chapters, whittled the less necessary diagrams and 
applied the blue pencil to some of the text. 

One could argue with the choice of material to 
be omitted: Chapter 5, on Recording Level Indica- 
tors, renamed Volume Indicators has some useful 
information expunged and five whole pages on pre- 
amplifier design have been dropped from Chapter 
8. It is perhaps fortunate that the excellent chapter 
on motors has been tidied and retained. 

More serious is the information that should have 
found its way into a new edition to bring it more 
up-to-date. There is still no admission that alterna- 
tive systems to NARTB exist. DIN/CCIR would 
seem to be a myth, and in the chapter on equalisa- 
tion this error is compounded by a complete 
avoidance of explanation of the time-constant 
specification of recording characteristics: quite 
unforgiveable in a semi-technical work such as 



this. Again, quarter-track recording and the various 
facilities it affords are not mentioned, neither is 
videotape, and a passing reference to head-gaps 
gives a limitation of 0.00025in., now regarded as 
"barn-door" dimensions by the better manu- 
facturers. 

This is a pity, for the book as a whole is a 
commendable addition to the enthusiast's library. 
Despite which, this reviewer will cling to his 
original copy and hanker after the book that some 
British authority will some day produce along the 
same lines. Recommended — but with reservations. 
— HWH. 



= INSTRUCTIONS TO RADIO CONSTRUCTORS. 

= By R. H. Warring. Second edition, published by Museum 

= Press Ltd. 144 pages. Size 8J x 5ln. Price 15s. 

WHEREAS the first edition covered basic 
radio theory and the design and construction 
of simple receivers, the second edition is 
more ambitious and includes quite a lot more 
information. For instance, a chapter on the design 
and construction of home printed circuts has been 
added. Another new chapter deals with the design 
and construction of the smaller transistor receivers. 
The original series of circuit designs have been 
retained, as these are — to quote the author — well 
proven in performance. 

Some thirty pages of this book are devoted to 
appendices, which range from broadcast frequency 
details and how to calculate circuit component 
values to data on the valves and transistors speci- 
fied in the various circuits. An appendix is also 
included on receiver faults, but is not very com- 
prehensive. 

This book would make suitable reading for those 
who would like to begin constructing, yet have no 
knowledge whatever of the subject. — JRC. 



= TRANSISTOR ETCHED-CIRCUIT PROJECTS 

= By James Kyle. Published by W. Foulsham & Co. Ltd. 

= 144 pages. Size 8i x 5ln. Price 24s. 

THIS novel publication deals with the use of 
printed circuits in home constructed gear and 
contains a number of actual negatives for the 
boards used in the various circuits given in the 
body of the book. These circuits range from an 
extremely simple potential divider network — called 
the volter — to an 80 metre c.w. transmitter. 

The first chapter contains a lot of information 
on printed circuits, from which the average home 
constructor should be able to knock-up his own 
circuits at little expense. The following chapters 
deal with various projects, some very simple and 
which could be put together with a minimum of 
knowledge. — JRC. 



782 



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H.R.O. SENIOR TABLE MODEL TYPE M. 50 l-c/s- 

30 Mc/s with "S" meter and crystal filter In excellent 
fully checked and tested condition together with set of 
8 general coverage coils and mains P.S.U. 110-220 v. 
£26.10.0. Carriage and packing 30/-. 
RACK MODEL also available^! the same price. 

"S" Meter for H.R.O. Receivers, Brand new £2.10.0. 
Carriage paid U.K. 

CRYSTALS for H.R.O. In original National Union 
Housing, 25/-. P. 4 P. 2/-. 

VARIOMETER lor No. 19 seis, 17/6. P. & P. 3/-. 

TELEPHONE HANDSET. Standard G.P.O. type; 
new 12/-. P. & P. 2/-. 

INSET MICROPHONE for telephone handset 2/6. 
P. 4 P. 2/-. 

2KW ULTRASONIC GENERATOR together with 
power supply unit for 200-250 v. A.C. Complete two 
chassis with Interconnecting cables. Frequency 37 to 
43 kc/s adjusted by fine control. Peak output 12 kw, 
average output 500 w. Completely new with valves and 
manual, £65, carriage paid U.K. 

A.R.S8D. RECEIVERS. Fully reconditioned, £55. 
Rebuilt model £85. Carriage paid U.K. 

SPARES FOR A.R.88D. RECEIVERS. Ask for your 
needs from our huge selection. 

ULTRA MODERN POWER SUPPLY UNIT. Supply 
voltage A.C: 105, 110, 115, 200, 205, 210, 220, 225, 230, 
240, 245, 250 v. Available voltages D.C. 

(a) 1700-1900 v. Stabilised, adjustable approx. 1 mA. 

(b) HT2 approx. 45 mA. 

(c) 260-350 v. stabilised, adjustable, approx. 45 mA. 

(d) 450 v. approx. 30 mA. 

(e) 50 v. approx. 150 mA. 

(0 4.5 v. A.C. 4.5 amp. common earlh. 

(g) 6.3 v. A.C, 4.5 amp. common earth. 

5 valves, 7 silicon rectifiers, 4 Solenlum HV rectifiers. 

Brand new, £9.10.0. Carriage 12/-. 

ARC 27 TRANS-RECEIVER. Aircraft 1750 Channel 

set. Price on request. 



PHASE MONITOR ME-63/U. Manufactured recently 
by Control Electronics Inc. Measures directly and 
displays on a panel meter the phase angle between 
two applied audio frequency signals within the range 
from 20-20,000 c.p.s. to an accuracy of rrf-O". Input 
signals can be sinusoidal or non-sinusoidal between 
2 and 30 v. peak. In excellent condition together with 
handbook and necessary connector. £45. Carriage 30/-. 
CR 150/6 RECEIVER. 2-32mc/s. in 4 bands. Double 
conversion. Miniature valves. 8 posltionslst oscillator 
selector, variable band with 100c-13kc built In cali- 
brator, 4kc bandspread, valve metering and signal 
indicator. Noise llmiter, £40. Original P.S.U. £7.10.0. 
Carriage 20/-. 

BC 221 FREQUENCY METERS. 125-20.000 kc/s- 
Accuracy 0.01%. Complete with individual calibration 
book. Fully tested in as new condition. With head- 
phones, £35. Carriage 10/-. 

MAINS P.S.U. for the above, specially built to fit 
battery compartment, £11.10.0. Carriage 5/-. 
BOONTON STANDARD SIGNAL GENERATOR 
MODEL 80. Frequency 2-400 Mc/s in six ranges. A.M., 
400 and 1.000 c/s. and external modulation. Provision 
for pulse modulation. Piston type attenuator, O.lv.V- 
100m V. Separate meter for modulation level and carrier 
level. Precision fiywheeling. 117v. A.C. input, £95. 
Carriage 39/-. 

SIGNAL GENERATOR TYPE TS 418. Signal 
frequency 400-1,000 Mc/s, direct calibration. Pulse rate 
40-400 c (x1 or x10), pulse delay variable, less than 
3'iscc to more than 300;j sec. Pulse with variable 'ess 
than 1 |isec. to more than 13>j.sec. Polarity— internal or 
external sources, positive or negative pulses, AM and 
CW. Output attenuator 0.2;/.V to 200mV. continuously 
variable. In fully tested condition, £150. Carriage paid. 



P. C. RADIO LTD. 

170 G0LDHAWK RD., W.12 

SHEpherd's Bush 4946 



C.R.100 RECEIVER. 60 kc/s-420 kc/s„ 500 kc/s.- 
30 Mc/s. In 6 bands, 2 HF stages, 3 IF stages. AVC on 
both phone and CW. Excellent condition, correctly 
tuned and guaranteed, £31. Carriage 30/-. 
TEST SET TS 125/AP 5 band RF power meter. 
Compact battery operated, UHF wattmeter used In 
checking the relative power output or Radar Tx. Can 
also be employed In measuring antenna radiation 
patterns and standing wave ratios. Freq. 2,400-3,335 
Mc/s. Consists of a temperature compensated Thermo- 
ster Bridge, a mu Ill-wattmeter and a horn type pick-up 
antenna. £30. Carriage 10/-. 

32;44FT. AERIALS each consisting of ten 3ft., Jin. 
dia. tubular screw-In sections. 14ft. (7 section) whip 
aerial with adaptor to fit the Jin. rod, Insulated base, 
stay plate and stay assemblies, pegs, reamer, hammer, 
etc. Absolutely brand new and complete ready to 
erect, in canvas bag, £3.9.6. P. & P. 10/6. 
MARCONI SIGNAL GENERATOR TYPE TF 
801B/3/S. Frequency range 12-485 Mc/s In five ranges. 
Directly calibrated frequency dial. Output waveform: 
CW. sinewave A.M., pulse A.M. (from exf. source 
only). Internal modulation frequency 1,000 c/s. Output 
a, normal — continuously variable directly calibrated 
from 0.1 }iv.— 0.5 v. b. high; up to 1 v. modulated for 
2 v. unmodulated, output impedance 50 ohms. Fine 
frequency tuning control, carrier on/off switch, built-in 
crystal calibration for 2 Mc;s and 10 Mc/s. Stabilised 
voltage supply. In excellent "as new" condition. 
Laboratory checked and guaranteed. £115. Carr. 30.'-. 
Including necessary connectors, plugs and Instruction 
manual. 

MARCONI VALVE VOLT METER TYPE TF 428-B. 
1.5 v. to 150 v. RMS in five ranges. A.C and D.C 
stabilised power supply. Complete with probe unit 
for RF measurements 200-240v. A.C. mains. In new 
condition and Laboratory tested, £12.10.0. Carriage 
10/-. 

TELETYPEWRITER TEST SET TS 659/UG £15. 
Carriage 10/-. 

TEST SET CALIBRATION TS 250A. Necessary 
for repairs and calibration of voltmeters £12.10.0. 
P. 4 P. 10/-. 



| | Open 9-5.30 p.m. except Thursday 9-1 p.m. PERSO NAL CALLERS WELCOME 



783 




784 




785 




The only set of its kind in the world 



BUILD IT YOURSELF 

£5.19.6 



# 7 Transistors 

For use both as an 
FM Tuner and pocket 
receiver 

Needs no alignment 

Pulse counting 
discriminator 

Tunes 88-108 Mc/s 

Signal to noise ratio : 
30tll> at 30 micro V 

£ Sizes: 2||x1 jixfin. 

£ Anyone can build it 

TECHNICAL DESCRIPTION 



This unique, superbly engineered super- 
net FM set is completely professional in 
styling inside and out. Designed essen- 
tially for the listener seeking the best 
possible quality, the performance of the 
Micro FM is fantastic. It is the only set in 
the world which can be used both as an 
FM tuner and as an independent FM 
pocket receiver just whenever you wish. 
Where problems of alignment have pre- 
viously made it impossible for a con- 
structor to complete an FM set for him- 
self have been completely eliminated in 
this unit, and it is ready to use the moment 
you have built it. The pulse counting dis- 
criminator ensures best possible audio 
quality; sensitivity is such that the 
telescopic aerial included with the kit 
assures good reception in all but the very 
poorest reception areas. The Sinclair 
Micro FM will give you all you want in 
FM quality reception as well as the 
satisfaction of building a unique design 
that will save you pounds. 



Complete kit inc. telescopic aerial, 
case, earpiece and instructions. 



SINCLAIR STEREO 25 

ALL-PURPOSE DE-LUXE 
PRE-AMP/CONTROL UNIT 



Here is a pre-amp/control unit designed for 
the exacting enthusiast wishing to have the 
very best. It incorporates the finest possible 
matched components in circuitry developed 
specially by Sinclair Radionics own research 
laboratories. The SINCLAIR STEREO 25 Pre- 
amplifier and Tone Control Unit is ideal in any 
stereo system where it is intended to take 
fullest advantage of today's best amplifier and 
auxiliary equipment systems. When the output 
from the stereo 25 is fed to two Z.1 2s, there is 
even great advantage in the appreciable saving 
in what you need spend to get first class hi-fi. 
In appearance, the Stereo 25 reflects the pro- 
fessional elegance which characterises all 
Sinclair designs. The front panel is in solid 
aluminium brush finished and polished in 
horizontal sections. Solid aluminium knobs are 
fitted. Mounting the unit is simple and it will 
enhance any hi-fi furnishing scheme in which 
it is used. A PZ.3 is recommended for powering 
the Stereo 25 and two Z.1 2s stereo assembly. 
For complete hi-fi coverage a Sinclair Micro FM 
should be used for the radio section. 



Double-purpose FM unit using 7 transistors and 
2 diodes. R.F. amplifier is followed by a self- 
oscillating miser and three stages of I.F. ampli- 
fication. The low I.F. employed in this set 
enables the problems of I.F. transformers 
and alignment to be eliminated. A pulse- 



counting discriminator ensures better audio 
quality. One output is for feeding to amplifier or 
recorder and the other enables the Micro FM to 
be used as a pocket receiver. A.F.C. "locks" the 
programme tuned in. The telescopic aerial 
included is sufficient in all but the worst signal 
areas. 




TO BRING THE BEST OUT OF ANY HI-FI EQUIPMENT 



TECHNICAL DESCRIPTION 

Performance figures obtained with the ^ 
Stereo 25 fed to two 2.12s, powered by 
a PZ.3. 

% SENSITIVITY for 10 watts into 1.5. i 
ohms load per channel. 
Mic— 2 mV into 50K ohms. < 

Pick-up— 3 mV Into 50K ohms. 
Radio— 20 mV into 4.7K ohms. 

% FREQUENCY RESPONSE (Mic. 
and Radio)— 25 c.'s to 30 kc/s ±1dB 
extending to 100 kc/s I 3dB. 

% EQUALISATION— Correct to with- 
in - 1dB on RIAA curve from 50 c/s 
to 20 kc/s. 

• SINCLAIR MICR0MATIC 



) TONE CONTROLS 

Treble-! 12dB to -10dB at 10 kc/s. 
Bass- 15dBto — 12dB at 100 c/s. 

) size t.Vi. X 2Jin. X 2Jin. overall, 
plus knobs. 

( FINISH— Front panel sectioned in 
brushed and polished solid alu- 
minium with solid aluminium knobs. 
Black figuring on front panel. 
Ready built, tested and guaranteed- 

£9.19.6 

See previous two pages 



SINCLAIR PZ.3 
POWER SUPPLY 
UNIT 

Transistorised techniques 
are used to achieve phe- 
nomenally good smoothing, 
thus assuring ideal operat- 
ing conditions. Ripple is a 
barely measureable 0.05 v. 
Will power two Z.12s and 
the Stereo 25 with ease. 

79/S 




SINCLAIR RADIONICS LTD, 22 Newmarket Rd., CAMBRIDGE 

Telephone 52996 (STD Code OCA3) 



786 




SINCLAIR Z.12 

12 WATT HI-FI AMPLIFIER AND PRE-AMP 



12 WATTS R.M.S. 

OUTPUT (24 w. peak) 
15 WATTS R.M.S. Music 
Power (30 watts peak) 



IDEAL FOR HI-FI, 
GUITAR, CAR RADIO, 
P.A., INSTRUMENTA- 
TION. INTERCOM. Etc. 



Constructors and experimenters find that the amazing adaptability and 
rugged construction of this very powerful and exceptionally compact 
amplifier make it possible to use just one type of unit with outstanding 
success in an unusually wide variety of applications. Eight special H F 
transistors are used in a highly original circuit to achieve the charateris- 
tics demanded of any quality amplifier irrespective of price, yet this 
Sinclair unit costing only 89/6 includes its own integrated pre-amplifier. 
The Z.12 accepts radio, microphone and pick-up inputs. Detailed instruc- 
tions for connecting them, matched for mono and stereo, are given in 
the manual supplied with every unit. The Z.12 can be operated from anv 
supply between 6 and 20V., but where it is required to run the Z.12 from 
mains supply, the PZ.3 is recommended. Those wishing to have a ready- 
made pre-amp control unit can feed inputs via the Stereo 25 which, with 
two Z.12s. will provide the finest stereophonic hi-fi possible— and the 
saving cost is considerable. 



"May I congratulate you 
on your Z.12 amplifier. I 
find it excellent. " 
M.C.. Lancing Sussex. 

"I should like to express 
my very considerable 
satisfaction with the micro 
P.M. (It) worked perfectly 
from the moment the bat- 
tery was connected. (It) 
is equally as good as one 
which I have also used 
and costs over live times 
as much. " 
L.E.H.. Harrogate, Yorks. 



TECHNICAL DESCRIPTION 



Built, tested and 
guaranteed. Ready 
for immediate use. 
With Z.12 manual. 



89'6 



I Size 3in. x Ifjn. X IJIn. 

I Class "B" ultra-linear output. 

I RESPONSE 15-50.000 c/s i 1 dB. 
Suitable for 3, 7.5 or 15w speaker. Two 3D 
speakers may be used In parallel. 



• INPUT-2mVinto2kn. 

• OUTPUT— 12 watts R.M.S. continuous 
sine wave (24 w. peak); 15 watts music 
power (30 w. peak) 

# Signal to noise ratio better than 60dB. 

# Quiescent current consumption— 15mA. 



GUARANTEE 

Should ycu not be com- 
pletely satisfied with 
your purchase when 
you receii/e il from us, 
your money will be 
refunded in full and at 
once without question. 
In addition, the Sinclair 
Micromatic is guaran- 
teed for 5 years. 

Full Service Facilities 
lable to Sinclair 
customers. 



X 



USE THIS ORDER FORM FOR MICROMATIC. MICRO FM, Z12, STEREO 25 PZ3 






ft 



J 



To: SINCLAIR RADIONICS LTD.. 22 NEWMARKET ROAD, CAMBRIDGE 

Please send items detailed below: 



For which I enclose cash/cheque/money order 



NAME 
ADDRESS 



If you prefer not to cut this page, please quote PW.267 when writing your order 



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787 



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HH 
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42 4/6 

SOBS 6/6 
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snCD«U32/6 





dfm 


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PCCI8910/- 


S130 25/- 














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uuo 

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£3.16.0 
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30/- 
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PLEASE NOTE OUR NEW ADDRESS 



2 METRES 4 



The thrills of VHF Amateur Radio! Comp- 
lete Kit. 70-150 Mc/s. costs only 47/6 (by 
post, UK. 3/3 extra) also now available new 
transistor Short-Wave kit model TR2 10— 
180 metres, ideal for beginners to Ham radio 
via simplified "Easy-Build" step-by-stc-p 
Instructions from 79/6. Write today enclos- 
ing a stamped addressed envelope for liter- 
ature and full details. Overseas enthusiasts 
note we despatch to all parts of the world- 
local stamp OK for literature. "GLOBE- 
KING" (Regd.) precision standard products 
tried and trusted by Amateurs everywhere. 

JOHNSONS (Radio) 

St. Martins Gate, Worcester 



RAPID SERVICING OF TRANSISTOR 
EQUIPMENT 

Gordon J. King 

A systematic guide lo the servicing of transistor radio and television receivers, tape 
recorders and high fidelity equipment. Directed to the service technician changing 
from valves to transistors, students starting a career in electronics, and the enthusi- 
astic amateur, it describes semiconductors and transistors, their operating principles 
and circuitry, together with basic test procedures, and then concentrates on fault 
diagnosis in the various fundamental types of circuit— audio and video amplifiers. 
R.F. circuits and oscillators — each section concluding with a Fault Diagnosis 
Summary Chart. Chapters are devoted to the ordinary transistor portable receiver 
and practical advice on repair procedures. 

160 pages. 90 line and half-tone illustrations. 30s. 
from your bookseller or by post 32s. from 

NEWNES. Tower House, Southampton St., W.C.2. 




S LD E R I N G ?-** ***^& «**»i- 



Made by ANTEX — makers of the finest precision 
soldering irons in the world, this Soldering Kit 
contains everything you need for successful sol- 
dering. Unique plastic "tool-box" format (with 
space for iron stowage with plug) keeps every- 
thing where you want it. 

ANTEX LTD. GROSVENOR HOUSE, CROYDON, SURREY. MUNicipal 2774 5 



788 



r 



HOME RADIO LTD. 187 London rd., mitcham, surrey, cr4 2yq • 

HOME RADIO for 
QUALITY COMPONENTS" 



Phone: MIT 3282 



The Home Radio Catalogue lists some 6,000 quality 
components (1,000 of them illustrated), but the key 
word is "quality". Before we catalogue any item we 
make sure the article is of the high quality that our 
customers have been led to expect from us; so 
having bought your catalogue you can buy with 
confidence. Our catalogue is backed by the fastest 
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in the morning is invariably despatched the same 
day). 

Don't delay— join our happy throng of satis- 
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* To ensure speedy delivery of correspondence please 
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Please write your name and address in block capitals 

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HOME RADIO LTD.. Dept. PW. 187 LONDON ROAD. MITCHAM. 

CR4 2YQ 



FOOTBALL POOL COMPUTER CDJCOTr and three 
I'tber auahigue circuits, 4/6. 

DIGITAL COMPUTER CIRCUIT 
A simple digital Adder Subtnuior using switches 
and lamps only. A fascinating demonstration of 
Binary arithmetic. Full circuit, wiring diagram 
and notes on the Binary system, 3/6. 

NOUGHTS AND CROSSES MACHINE CIRCUIT. Uses 
standar<r miniature switches and lamps only. Thi« 
machine cannot be beaten. Full circuit," wiring 
diagram and Instructions, 3/6. 

1% High Stability Resistors 
| watt 1 "„. a/- each. Full range 1*1 ohm- to 10 Meg. 
stock List available. 

l°o Wirewound Resistors 
l°i 1 watt. 1 ohm to 6K, 3/3; to 20K. 4/6; '»• 
add 3d. Your value wound to order. 
200 Assorted 2 watt Resistors, 1% to 20°„. 12/6. 

PLANET INSTRUMENT CO. 

25 (W) DOMINION AVENUE. LEEDS 7 



WORLD RADIO & TV 
HANDBOOK 1967, 32/- 

by JOHANSEN. postage 1/3 

Transistor Specs, and Subs. Handbook 1967 ed. 

by Techpress. 22/6. P. & p. l/-. 

p a &'p w alve r>ata by ww - new 8th cd - 9 ' 6 - 
V.U.F- for the Radio Amateur by C.Q. 28/-. 

c. & P. 1/3. 

Hi-Fi Year Book 1967. 15/-. P. & P. 1/6. 

R.S.G.B. Amateur Radio (all Book 1967 ed. 

o/-. ir, 6£ P. 8d. 

R.S.G.B. Radio Amateur Examination 

Manual 1967 ed. 5/-. P. & P. 8d. 

Transistor Pocket Book by Hibbeard. 85/-. 

Where possible 24-hour service guaranteed. 

UNIVERSAL BOOK CO. 

12 LITTLE NEWPORT STREET, 
LONDON, W.C.2 

(Leicester Square Tube Station* 







£2 

POST FREE 
On your own 

TRANSISTOR PORTABLE' 

* Boosts Pirate and distant stations. 

* , N ' pl:,g \T: s £ ""■"- i: *M Pi*™ 

Dewtron Wave Trap near radio. 

* Kvtends Battery life — reduces lading'. 
■*• L'se in car. caravan. Without aerial. 

with pps battery (We several mouths). 

D.E.W. LTD.. Dept. P.W.. Rinewood Road. 
FERNDOWN. Dorset. 



tHtAtAi/vwAxu* PRECISION SOLDERING KIT 

This is what the ANT EX Kit contains : 



• Model CN240 15W Precision Iron with 3/16" bit, (used 
in electronic workshops and factories all over the world) 

• Two spare Interchangeable Bits (5 32" and 3 32") 

• Reel of resin-cored Solder 

• Handy Heat Sink • Cleaning Pad 

ryyC 36-paae booklet on "How-to-Solder"— a mine 
of information for amateur and professional. 



BRING YOUR WORKSHOP UP-TO- 
DATE with the new ANT EX KIT 

Obtainable from 
radio and electrical 
shops everywhere. 



ew AIM I tX Kll 

49'6 



AIMTEX LTD. GROSVEIMOR HOUSE, 
CROYDON, SURREY. MUNicipal 2774/5 



Practical Wireless Classified Advertisements 

The pre-paid rate for classified advertisements is l/6d. per word (minimum order 18/-), box number l/6d. 
extra. Semi-displayed setting £4. 12s. 6d. per single column inch. All cheques, postal orders, etc., to be 
made payable to PRACTICAL WIRELESS and crossed "Lloyds Bank Ltd." Treasury notes should 
always be sent registered post. Advertisements, together with remittance, should be sent to the Advertise- 
ment Manager, PRACTICAL WIRELESS, George Newnes Ltd., Tower House, Southampton Street, 
London, WC2, for insertion in the next available issue. 



METAL WORK 



METAL WORK: All types cabineis, chassis 
racks, etc., to your specifications. PHILPOTTS 
METAL WORKS LTD. Chapman Street, 
Loughborough. 



SHEET METAL PUNCH (Pat. App. No. 
309050/66), with Punch and Die for one size 
19/6. P. & P. 4/-. Clearance sizes availabfc, 
i" -ft" i" -ft" 2" ! i«" Send for leaflet. 
J. MOIR (TOOLS), 81 Oldham Street, Hyde, 
Cheshire. 



EDUCATIONAL 



RADIO OFFICERS see the world! Sea-going 
and shore appointments. Trainee vacancies 
during 1967. Grants available. Day and 
Boarding students. Stamp for prospectus. 
Wireless College, Colwyn Bay. 



"BECOME "Technically qualified" in your 
spare time, guaranteed diploma and exam. 
home-study courses in radio. T.V. servicing and 
maintenance. T.T.E.B., City and Guilds, etc: 
highly informative 120-page Guide — free. 
CHAMBERS COLLEGE (Dept. 857K), 148 
Holborn, London. E.C.I." 



CITY & GUILDS (electrical, etc.) on 'Satis- 
faction or Refund of Fee' terms. Thousands 
of passes. For details of modern courses in all 
branches of electrical engineering, electronics, 
radio, T.V.. automation, etc., send for 132 
page Handbook— FREE. B.I.E.T. (Dept. 
168K) Aldermaston Court, Aldermaston, 
Berks. 

RADIO OFFICER training courses. Write: 
Principal, Newport and Monmouthshire 
College of Technology, Newport, Mon. 



MISCELLANEOUS 



CONVERT ANY TV SET into an Oscilloscope. 
Diagrams and instructions 12/6. REDMOND, 
42 Dean Close, Portslade, Sussex. 

—ELECTRONIC MUSIC?" 

Then how about making- yourself an electric 
organ? Constructional data available — 
full circuits, drawings and notes! It has 
5 octaves. 2 manuals and pedals with 24 
stops — uses 41 valves. With its variable 
attack you can play Classics and Swing. 
Write NOW for free leaflet and further 
details to C & S.. 20 Maude Street, 
Darlington, Durham. Send 3d. stamp. 



SERVICE SHEETS 



SERVICE SHEETS. Television. All makes all 
models. Great new selection. Over 3.000 types. 
Only 3/- each. Post Paid. D. & B. 
TELEVISION (WIMBLEDON) LTD.. 131 
Kingston Road. South Wimbledon, London, 
S.W.I9. Tel.: CHErrywood 3955. 

SERVICE SHEETS for all makes. Radio, T/V, 
Tape Recorders, 1925-1966. Prices from I/-. 
Catalogue 6,000 models 2/6d. Free fault- 
finding guide with all Sheets. Please send 
stamped addressed envelope with all orders/ 
enquiries, HAMILTON RADIO, Western 
Road, St. Leonards, Sussex. 

SERVICE SHEETS, Radio TV. 5.000 models. 
List 1/-. S.A.E. inquiries. TELRAY II 
Maudland Bank. Preston. 

SERVICE SHEETS (75,000) 4/- each. Callers 
welcome. Always open. 5 South Street, 
Oakenshaw, Bradford. 



City and County of Bristol 
BRISTOL TECHNICAL COLLEGE 

Principal: E. Poole, B.Sc.Eng., M.I.Mech.E., M.I. Prod. E. 

CAREERS IN RADIO & RADAR 



Marine Radio Officers 

2-year full-time course for young men 

aged 16 upwards, leading to 1st and 2nd 

class P.M.G. Certificates and B.O.T. Radar 
Maintenance Certificate. 

Conversion Course (2nd Class to 1st Class). 

R.T. Course (for Full or Restricted Licence). 



Licensed Aircraft Radio 
Engineers 

2-year, full-time course for A.R.M.E. Licences, 
categories A & B, and 6-months courses 
for Radar Rating in association with the above. 



SERVICE SHEETS 



Training given on the latest types of Marine and Aircraft Equipment in newly equipped 

Laboratories at 

THE SCHOOL OF MARINE RADIO AND RADAR 

Senior Lecturer: F E. BARLTROP 

For details write to: 

THE REGISTRAR 

BRISTOL TECHNICAL COLLEGE 

ASHLEY DOWN, BRISTOL 7 



RADIO TELEVISION over 8.000 models. 
JOHN GILBERTTELEVISION. IbShepherds 
Bush Rd., London W.6. SHE 8441. 

SERVICE SHEETS 

4/- each, plus postage 

We have the largest display of Service 

Sheets for all makes and types of Radios 

and Televisions, etc., in the country. Speedy 

service. 

To obtain the Service Sheet you require 

please complete the attached coupon. 

Name: 

Address: 

To: S.P. DISTRIBUTORS 

30 Baker Street, London, W.1 

Please supply Service Sheets for the following 

Make: 

Model No Radio/TV 

Make: 

Model No Radio/TV 

Make: 

Model No Radio/TV 

I require the new 1967 List of Service 
Sheets at 1/6 each plus postage. 

(please delete items not applicable) 

I enclose remittance of 

(which includes postage) 

MAIL ORDERS ONLY (Feb.) PW 

FOR SALE 
ELECTRIC SOLDERING IRON 



FANTASTIC 
BARGAIN OFFER 

Lightweight Pistol Grip handle 
40 watt. 240/25UV. A.C. Detachable 
handle forms cover for iron when 
not in use. With 4ift. Safety 
3-core flex. Indispensable for 
every home handy- 
man. A boon to model 
makers and a necessity 
for every wireless en- 
thusiast. Offered to 
you at this new amazing 
price. 

C. H. SERVICE (Dept. P.W.) 

Lusted Hall Lane, TatsfielU, Kent. 




790 



FOR SALE 

(continued) 



TVn£" FACTORY CLEARANCE: Radio 
iv tiectncal Components in mixed parcels, 
txample: 22 b. mixed parcel £1, p.p. 7/6. 
Speakers, grilles, valves, bases, i.f.s. covers 
condensers, etc. Hundred other items. S.A.e! 
list and postal order to P. NEWTON 16 
Shalcross Crescent, Hatfield. Herts. 



SPECIAL OFFER 
GEVAERT TAPE. New. Boxed, 54, 600ft 
with Stop and Leader Tapes 9/- or 6 for 
:>0/-, post paid. 

GRUNDIG MAI. 2 Transistor Pre-amps 
tor rape Monitoring or Microphone 
Boosters, 57/6, post paid. 

LIST PRICE 4 GNS. 

LEE ELECTRONICS 
400 Edgware Road, Paddington 5521 
Send for Free Lists and details of above 



MANUFACTURERS varied surplus, experi- 
menters send for list. HATFIELD, 7 St. George 
Bungalow, Hildenborough, Kent. 



raff -STORl ff^^f *- *&£•'— 

Set these AIR DRYING GREY HAMMER 

b L ack'WR1NKLE(CRACKLF). 



.•n Ettih 



■-■Jt 



Na 



Hi 



i!"I'' 



r-.J rc3 



II Blatk Wrinkle (Cr«ll 
ir counter or IS/I I. carriage paid! per puih- 
10 lelMony r an, Alio Durable, lira, and water 
*.?',, ? hck ."'" r ""' h (12 on. lell-ipra, C an S 
13.11 carnace paid. 



nil framferabl* 
aolouri and pnmti 



S?EC'AL OFFER: I "ea~n pi 
jnap-on trigje- dandle (value 5/-j I 
pa>d Cno.ee o/ 1 3 itiripr,, piatn 
,r!otor ear ,u.l.i,) alio MkUa, 
Pleaic encloso;cheque or P.O. for total amounc CO 
tUKAN. Dept. 307a Edjwa.e Rrf,. London W.2 

i all day Saturday. <;,„„, j^ 



(Open all day Saturday, 
Closed Thursday afternoon) 



TRANSISTORS 

SPECIAL OFFER 

1 watt S.T.C. 300 mc/s N.P.N. 
Silicon Planar, Transistors limited 
stocks £1 for 6. 

WITH DATA 



3/- each. OC44, OC45, OC70, 
OC71, 0C81, 0C81D, OC200, 
GET16, GET20. 

4/- each. AF114, AF115, AF116, 
AF117, OC170, 0C171. 

5/- each. OC139, OC140, GET7, 
GET8, GET9, XC141, BY100, 
0A211. 



BSY27 7/6 each OC20 10/- each 



ZENER DIODES 

All volts between 3.9v. and 26v. 
£w 3/6 each, 1.5w 5/- each, 
7w 6/- each. 



Send 6d. for full lists: — 
inc., S.C.R., Zeners. 

CURSONS 

78 BROAD STREET 
CANTERBURY, KENT 



FOR SALE 

(continued) 



LEE ELECTRONICS 

The Tape Recorder and Hi-Fi Specialists 

n' n !^IffeV X w 4 "T I ?. ck , St;ereo P nonl c/Monophonlc 
Offe^S/i^ch LlSt Price 6 SDS - S^ '^ 

vVSFJ^i? 4 "tJ ra f k Stereophonic/Monophonie 
Offer Ipm^o,? 6 ^ 5 - List , P^ce £3.10.0. Special 
S, •gS.S^PS- °F supplied together (one of 
each) at £3.17.6. (Send S.A.E. for details.) 
Ail Heads are supplied complete with fixing 
Plates and Technical Specifications. ^^ 

ra™ f o a J?i la . ble_ f A P ?, T 2-Speed Direct-Drive 
£3-10.0? Post > Paid 1S £12 "°'°' Special ° ffer 

00 EOGWARK ROAD, PADDINGTON, >V3 
Pnddington 55'il 



MORSE ^s d y ! 

£?£ ff™ " 3 RHYTHM RECORDED COURSE 
minimSm. PraC Ume down to ^ abs °lut* 
One student, aged 20. took only 13 DAYS 
SESi ^ otlae ''- aeed 69, took under a week to 
J,?, a i i „.?. wpn V Ir y° u wish to read Morse easily 
?™ iS acura l y pl , ease e °olose 8d. in stamps or 
two international reply coupons for full explana- 
tory leaflet to : G3CHS/P. -immi 
45 Green Lane, Purley, Surrey, UPLands 2896 



HAMMERITE 



HAMMER PATTERN 
BRDSH PAINT FOR 
PANELS. METALWORK 
3/6 TIN • JUST BRUSH ON • 
WITHSTANDS 150'C. OIL. WATER ETC. 

2J o*. tins .... 3/6 j ga |i, m 35/.. 

} P n ' 7/6 1 gallon 58/-' 

1 Pint .... 15/- ('sent byroad) 

Carriage: Orders up In 5/-, 1M.: tip to 10/-, 1/9; 
over 10/-, 3/-. Colours: blue, silver, black or broiuv. 
Ketura of post service, Monday to Friday. 

From //our component *hop or direct from the 

^^ manufacturer: 

FINNIGAN SPECIALITY PAINTS (PW) 

Mickley Square, Stocksficld, Northumberland 

Tel. Stocksneld SS280. 



WANTED 



VALVES WANTED, brand new popular 
types boxed. DURHAM SUPPLIES (C), 
175, Durham Road, Bradford 8, Yorkshire. 

WE BUY New Valves and Transistors. State 
price. A.D.A. MANUFACTURING CO., 116 
Alfreton Road, Nottingham. 

DAMAGED AVO METERS wanted. Models 
7 and 8. Any condition. Any quantity. 
HUGGETTS LTD., 2-4 Pawson's Road, West 
Croydon. 



WANTED: Popular Brand New Valves. R.H.S. 
Stamford House, 538 Great Horton Road. 
Bradford 7. 



WE BUY New Valves for cash, large or small 
quantities, old types or the latest by return. Send 
details. Quotations by return. WALTON'S 
WIRELESS STORES, 15 Church Street, 
Wolverhampton. 



WANTED NEW 
VALVES ONLY 

Must be new and boxed 
Payment by return 

WILLIAM CARVIS LTD 

1 03 North Street, Leeds 7 



BOOKS & PUBLICATIONS 



A GUIDE TO SURPLUS 
COMMUNICATION RECEIVERS 

A detailed guide to thirty-one receivers, 
including the HR0, AR88. CR100, R107 
R1155. PCR, 52 set. etc. 
7/6, P. & p. i/_. MaU order only t0 . 
ADKINS. 72 Courtenay Ave, Harrow 
Middlesex. 



SURPLUS HANDBOOKS 

!?« e '?;. cui,andNo,es •• •■ «/6p/p6d. 

1155 set Circuit and Notes .. .. 4/6 p/p 6d. 

H.R.O. Technical Instructions . . 3/6 p/p 6d. 

38 set Technical Instructions .. 3'8p/p6d! 

46 set Working Instructions .. .. 3/6 p/p 6d 

^. S fl TeChnicallns,ruc,ions •• 5/-p/p6d.' 

BC.221 Circuit and Notes .. .. 3/6 p/p 6d. 

Wavemeter Class Tech. Instr. . . 3/6 p/p 6d 
18 set Circuit and Notes .. .. 3/6 p/p 6d 

BC.1000 (31 set) Circuit and Notes . . 3/6 p/p 6d. 
CR.100/B.28 Circuit and Notes .. 8/6 p/p 9d. 

R.107 Circuit and Notes .. .. 5/- p/p 6d. 

AR.88D I nstructlon Manual . . . , 15/. p / p ,/6 

62 set Circuit and Notes .. 4/6 p/p 6d. 

Circuit Diagrams 3/- each post free. R.1116/A. 
R.1224/A, R.1355, R.F. 24. 25 and 26, A.1134, 
T.1154 (all models), BC.312, BC.342, BC.348j! 
BC.348 (E.M.P.), BC.624, 22 set. 
52 set Sender and Receiver circuits 6/- post free 
Resistor colour code Indicator, 1/6 p/p 6d. 

S.A.E. with all enquiries please. 

Postage rates apply to U.K. only. 

Mail order only to: 

INSTRUCTIONAL HANDBOOK 
SUPPLIES 

DEPT. PW, TALBOT HOUSE, 
28 TALBOT GARDENS, LEEDS 8 



SOUND RECORDINGS 



^w 10 -^ T J¥ E BUY! ToD brand 7in - 
2,400ft 25/-; 5Jin., 1.200ft. 15/-. P. and P. 

'• at H'\ 2 r at J 19 - 3 " 6 at 3 ' 6 - Bargains in all 
r Z n- ?™ E " f ?T, ,,s 4: E.C. KINGSLEY AND 
?°\, LT J?- 93 Tottenham Court Road, 
London W. 1 ., EUSton 6500. 

RECEIVERS & COMPONENTS 



CQ ALL HAMS Telephone sets "L" Mk. 1 with 
batteries 36/- each or 58/6 pair. Carbon hand 
?y£: es x rf 7/6, Rem ote control units No. 2 
•', • V".?,-, 10 P added moving coil head phones & 
mike 12/6. 3 gang 500 Pf tuning capacitors new 
& boxed 8/6. 19 set morse keys 7/6. 6V6 & 807 
JS , «KKu£f£! paid - SAE lists. G. WEBSTER 
(ELECTRICAL) 9a Greyfriars Road, Cole- 
ham, Shrewsbury. Shropshire. 



AJ. POST FREE BARGAINS 
SPECIAL OFFERS AXE BRAND NEW 

V/controls w/wound s.p. switch 2Sk or 50k 479 
V/controls carbon less switch all values 3/8 
V/controls carbon D.P. switch all values 5/9 
Mixed resistors per 100 7/6 
12ATJ7. 6/- PCF80. 5/-. 
3w. Record Player Amplifiers, 84/-. 
2-way socket panels 9U. each. 4/9 dozen. 
Recording TAPE 

3in. 300ft. 4/9 3in. 150ft. 3/3 
5iin. 1800ft. 20/- 5in. 900ft. 12/- 
7in. 1800ft. 19/- 7in. 3600ft. 57/6 
3in. 600ft. 12/6 3in. 225ft. 3/9 
5in. 600ft. 8/3 5fin. 1200ft. 14/6 
7in. 1200ft. 14/3 4In. 900ft. 14/6 
3 Reels and over 5% discount 
S.A.E. All enquiries. Satisfaction guaranteed. 
A.l. RADIO COMPONENTS 
14 The Borough Canterbury Kent 



791 



RECEIVERS & COMPONENTS 

(continued) 



TRANSISTORS, UNMARKED. UNTESTED. 

40 for 10/-. p. and p. I/-, 4 packets post free. 
Relays, thousands of types, special catalogue 
free. General catalogue of Mechanical and 
Electrical Gear. Tools, etc. (5.000 items) tree. 
K. R. WH1STON (Dept. PRW). New Mills. 
Stockport. 



RECEIVERS & COMPONENTS 

(continued) 



MULLARD TRANSISTOR 
BARGAIN 

Brand new first grade— fully guaranteed. 

OC44. OC81D, OC81. OC73, any 5 pieces 10,'- 

post paid. 

Matched Output Set OC81D + pair OC81 7/- 

post paid. 

Matched RF Set OC44 - pair OC45 8/6 post paid. 



100 piv 750 mA Silicon Rectifiers 8 pieces 10/-. 
2N2926 Planars gain spread 150-300 3 pieces 11,-. 
KS31W Thermistors 8 K ohms at 20°C2/-each. 
1 500- 2000 M FD at 25V W KG. Capacitors 3/- each. 
CATALOGUE. Our 16 page list contains prices of 
hundreds of Semiconductors, circuits and handy 
reference section— Send 1- stamps. Postage, 9d. 
per order. 

L.S.T. COMPONENTS 

23 New Road Brentwood Essex 



EXPERIMENTER'S 

PRINTED CIRCUIT KIT 

The Kit contains 4 copper laminate board* lo suit 
tbe derigM enetoeed ;S in chemical- wpfred*™ 

etching. 16-pagc Kicking Manual I RLNTLli 
, I H| in - Fill: \M \ I l.l BS". '-> miniature ra.Hu 
1 1 each kit . . . Essential 
DedCD Data. Circuit-. Layouts, Chassis Plans etc. 
(or building. 

30 SUGGESTED PROJECTS 

lju.-t v.rv .-fli. ftntf olectaODle dedgw yo" probably 

haven't heard of yet . . . 



COMPONENTS, transistors ex-W.D. and 
surplus. Call at ROGERS. 31 Nelson Street, 
Southport. (List 6d stamp.) 



TRANSISTORS 

For the short wave experimenter. All brand 
new at economy prices. Guaranteed. 
Silicon NPN. 2N2926. 100 M/c, 4/-. ME 301 1. 
800 M'c, 5/6. 2N3662. 1200 M/c. 13/-. 2N697. 
50 M/c, 2 watt, 13/-. BFYI7, 245 M/c, 25 watt, 

Germanium PNP. AF139. 800 M/c 13/6. 
GM290, 800 M/c. 16/6. AFYI9, 225 M/c. 
08 watt, 24,'-, Send' stamp for lull list. 

G. ELLIOTT 
3 Sandgate Avenue, Tilehurst, Reading, Berks. 




RECEIVERS & COMPONENTS 

(continued) 



. . . Including 4 crystal sets. 4 Amplifiers. 2 Intercom*. 
4 Pocket Loudspeaker Radios. Triple Keflex with 
self-adjust tag regeneration. Bactem-Povrered Radio 
Match!")-; Radio. Radio Control Receiver. Control 
,„ , tell bv induction <uot radio). Human "Body- 
Radiation "Detector. Efficient Burglar Alarm. 
Man 'Woman Discriminator. Perpetual Motion 
3 SUBMINIATTJRE RADIO DESIGNS, 
smaller than anvthlng so far published anywhere in 
the World. Kin* ita-i... Wrist-Wat, h Radio. Postage- 
Staiim Hadio. Thermal Proximity Fuse. Pocket 
TransceiveriorlOin band (licence required). Transis- 
tnr Tester. Light-Seeking Robot, etc. eic. Price oi kit. 
8/6. Post 4: Packing 1/6. Bend S.A.F.. for Details, 
Photographs. 

"YORK ELECTRICS" 

181a York Rd.. London S.W.ll 



BI-PAK SEMICONDUCTORS 



8 RADNOR HOUSE 

93/97 REGENT STREET 

LONDON, W.1 



LOW COST SILICON CONTROLLED "^ 'y^^S 

-.can, JAW crmnw V"' »%!2Sm£ 

EACH l'l\ EACH fjy nau , Ummm limyil Con 



1 AMP (TO 

PIV EACH 

80 W 

100 9/8 

aoo -- ,; 

400 --" 

__-_._. One 10.- Pack of >v 

FREE choice nee urn, 

■ ■■■-■" valued M or ox 



ioo io/6 ioo me 

400 30/- WO 30- 

600 43/- 600 ....... 5a/- 

tOC PIV Power SCR 30 Amp, Special 1 n. 



including 
Light 
Dimmers, Speed Controllers. 
AC Power Switch, etc., with 
SCR order* or on request. 



FREE 



logic afODCLBS C D C C 

and(or, Gates, Memory trm*, rrtCC 
limer Units, etc., details free 



VALUE "« 50 



TUANS1STOR8 

ITJXHD 

UNTESTED 



8' QCIS9 Trim.-. NPN" Milliard .. 
2 Drift Trans. 2N1225 100 M < ':■ I'M' 
6 Matched Trans. OC44/48/81/81D . . . 
4 OA10 Diodes Mallard 

15 Red Spot AF Tran*. PS* 

16 White Spot KF Trans. PNP 



10/- 

. |M- 

. 10/- 

. 10/- 

. 10/- 

. ill - 

10/- 



4 Bit Recta. HA 100 400 PIV . . . . fjr 

i MPS Tran,. OC1S6 2N1808, ETC. 

2 10 Amp. Mil. Kect. 50,' inn PIV . 

5 Dloda 4 (JA70.4OA79 

1 5 AMP SCR 100 PIV 

3 811. Trail*. 28803 PSP 



10/- 

III - 
10/- 
10/- 

lo,<- 



6 GET884 Trans. Eqvt. OC44 »•', 

10 Assorted Computer Diode* ""»< 

4 Zenera ». 6.8. 10. 12 Vlts 10'- 

4 2C417 Tran-. Bqvt. APUU 117 «- 

2 200 M I '- S :. Trans. BSY2U.27 10 " 

2 Bi-directional Trans. AS! »•• {"' 

4 High Current Trans. OC42 }«' 

2 Power Trans. OC26..35 !"', 

5 Sll. Reels. 400 PIV 250mA *U/- 

3 OC71 Tran-. Mullard *«', 

3 OC75 Trmna. Mullard ' J!" 

3 NPN Sll. Tran-. 70 M C* 

1 Power Trans. OC20 100 Vita 

OA47 Gold Bonded lliiales 

4 OA202 Sll. Diode* Sub-Mln 

3 OC77 Tran*. Mullard " ' 

8 OA81 Diode* CV449 «£ 

3 Sil. Boeta. 400 PIV aOO mA 



10- 
10.- 
10/- 
l«/- 



Our vast stocks change daily with hundreds oi 
ftuniconduclor bargain, becoming available Just 
lend 2/0 to cover 3 months mailing o( our latest 
Stoat Hits- eqvt. charts, circuit", ate. 



1« «nnf VSMAIIKEI), ONTBSTHDmb J 
SCR s voi - iA,ili BA SS? 1 A >"»ZU/- 
U OOII o 50-400 PIV '_ 

3 High vit. AF Trim*. PS P ACY17 15;- 

5 Sll. Rect. 750mA 100 PIV TEXAS 15 - 

3 BSYB5A Sll. Trans. STC «/- 

3 811. Trans. OC200 Milliard ... ..... . . . . 15 - 

2 Sll, Power Rect. 11 Amp. 200 PIV B^ Z13 . . 15/- 

1 AF139 GERM. Tran*. 3500 M/C* ... 16/- 

1 Sll. Power Trans. 100 M/C* TK201 A M'-\ . lo/- 

1 ■/ tat i Diode* 3- lovlt-. Mixed 4"iun« 15/- 

5 OAS Gold Bonded DioUes Mullanl Jo/- 

I 2M 132 PSP PLANAR Trans. Sil . 15/- 

i SN897 NPN PL A N Alt Trana. Sil ....... 15/- 

4 GEItM. Power Tran*. eqvt. OC16 Milliard 15 - 

1 0H1JUNCTION Trans. 2S2640 G.E lo,- 

2 Sll. Trans- fiOVCU 200 MJCs. ZT83/84 . . 15/- 
1 S,l. PLANAR Tran*. P.SY25 NPN lOOOM/Cs 15/- 

1 811. Trans. 1S104 150 M C* 1IPE 200 N PM W 

2 SCR's 50 PIV 1 Amp. TO-5 can 15/- 

1 Tunnel Diode DS870 (TD-5) O.B 15'- 

1 2N2100 L-NIJI.NiTION Tran-. TO-5 can.. 15/- 

2 Sil. Rect. 3 Amp. 400 PIV Stud , 15 - 

1 Tunnel Diode AEY11 STC. IoBUM/Cs .... 16- 
•1 GF.KM. Power 1 ran- 0038 2'.) 151- 

2 ZENER? 25 Wat I 1 * .M 22 Vlts ....... 15- 

G sil. Heel. Tvue BVHii'Mi* PIS ...iOiuA .. 20/- 

8 811. Kect. 400 IMV 200 SOOiuA fOI- 

1 Transistor Manual by G.F.. 648 pages .... 30 - 

1 Silicon Controlled Kect. .Manual G.B, ..... i<>:~ 

25 Mixed Sii. A GERM. Trans. New Marked . . 30 - 

40 Mixed Semiconductor* New Marked 40/- 

1 Logic Module Han.lbook «: Catalogue li<0 

Order 10/-. CASH WITH ORDER 

Add 1/- postage and packing per 

postal service. 



Minimum 

PLEASE 

Order, GUARANTEED by ix 

Overseas add extra for Airmail. 



WELL-KNOWN ARMY TRANS-RECEIVER MK. Ill 
ltanae 8-8 Me* R.T- M.C.W. and C.W . appr v.x ; _-ik 
it ?7 x lim. Power required IS vi.T. Receiver* 
T.X.50O V.-, ! ,.ii!v45/-orwilli235Mc > '. H.i Is BS. 
Section 15/- extra. Carr. both 10/-. Even tat Checked 
complete and in reasonable condition. Air tested 10/-. 
12 X.DC p.c. 15/-. New 30/-. Out. both BY-. Brand 

. ■ \ \ ,i . Power Unil for BeceJver.ln 
metal ease 12 V. and 275 V. complete wit). 12 pin ptag 
to =et onlv 70/- • c.l . for 1 .X. ai.u b.\- 

*upplving'l2 V.Il.t . 275 S an I 500 V. E7.10.0. po*t o -• 
Braid New Headset and Mike which plug* *l might mto 
set (specially made) 22/8. Brand New Set* t available at 
£6.10.0. New Aerial tuning units at 20/-. Pout 7/6. AR 
circuit* of unit- supplied. 

TOWNEND RADIO (DEPT. E) 
263 Wakefield Road. Bradford 4, York*. 



31 Set WTs. complete with 15 valves and 2 

crvstals. Operate up to 48 MEG tunable wltn 

circuit and details. No rear case. 25/-. eacli. 

Part post 5/-. 

Spare Set Valves and Crystals. 12/6. 

Chassis less valves. 12/6. P. & P- W"« 

No other spares available. 

Assorted High Stab Resistors. 7/6. 100. 

Assorted Syflex P.F. Condensers, 7/6. 100. 

Faxolin Sheet. ' !S " x 12" x 12', 3/-. 

Thin Paxolin Sheet, approx. V„ x 12' x 12". 

8 sheets for 5/-- 

White Plastic Sheet, approx. Vw" x 61" x 24". 

Suitable dials, insulation, case fronts, etc. 

4 sheets for 5/-. 

Small E.M. Counters. 5 digit. 500 ohm. 6/6. 

Bulgin Extra Sensitive Micro Switch. 5/-. 

P.O. Belay 2000 ohm. IB. 5/-, 1M. IB. 6/-. 

Key Switches. 4 pole, 2 throw. 3/6. 3 Position 

DP -i- DP centre off. 5/-. 3 c/o+4 c/o centre off. 

6/-. DP - DP 2 for 5/-. 

Plessey Plugs and Sockets, 12 way, SI- pr.. 6 way 

5/- pr. 

6 or 12 way screened cable to match, 3/- yd. 

Breast Mike. 6/-. Carbon Inserts, 1/6. 

Battery Ever-Beady. 90v+7lv. 4/6. 12 for 30/-. 

Small Component Boxes, 12/6, for 60 samples 6tl. 

Mil Metal Screen for 5[iP7 with fittings. 6/6. 

250mA Puses li'Xi*. 5/-. 100. 

100 volt Hand Generator. 7/6. 

Rheostat WW Rotary, 15 ohms, 3"6 amp, 12/6. 

Details of Instrument Case Assembly Free, 

send large addressed envelope. 

Rotary Transformer. Input 12 volts, output 

490v at 65mA. 9/-. 

Rotary Transformer. 12v. input. 300v output, 

at 0.2 amp.. 35/-. 

Modern lightweight Breast Mikes. Polythone 

fittings. New, 7/6. spare insert 2/6. 

Ernest Turner meter 2J' fitting (round) 1-0-1M/A. 

Centre zero. 12/6. 

Carpenters relay type 3SE1. 250 ohm-; 200 ohm 

each side. Fitted with plug in base. 17/6 each. 

Type 3000 P.O. relay. New 6000 ohm coil, 2 sets 
of change-over. 8/6. 

Transistors 2G302, 2/.- 

Printed circuit board. 11" x oi' ideal for reuse 
with 28 diodes CV448 plus some high stah resis- 
tors, 10/- post paid. 

A new range of instrument cases ready send for 
free list. S.A.E. please. 

Polestyrene capacitors 125 volts wkg., 120.000. 
Recent manufacture for computor co. Prices 
6<I. each. 5/- doz.. 25/- per 100. Your choice oi 
values stock up now and save pounds. FKfc,fc. 
sample with lists of values. 
Siemens High Speed Relay. S.P.C.O. 1000,+ 
1,000 ohms. 6/-. 

Small Sealed Relay 1.700 -r 1.700 ohms S.P.C.O.. 
6/-. 

P.O. Relay. 200 ohms 2 change over. 6/-. 
Mains transformer output 350-0-350V at 100 M/A 
+ 2 x 5v at 2A. 1 x 2v at 1A, 1 x 6.3v at 2a, lo/-. 
Extra Small Rotary Transformer by Hoover. 
12v in output 300v suitable razors etc. with cool- 
ing fan new boxed, 10/-. 



E. R. NICHOLLS 

Mail Order and Retail Shop 

4tl LOWKIEUD KOAI) 

Off SHAW IIKATH, STOC KPORT 

CHESHIRE 



792 



RECEIVERS & COMPONENTS 

(continued) 



COMPONENTS 

• ASSORTED CAPACITORS — New 

Paper, Polyester, Electrolytic, etc.. 100 off 9/6 

• ASSORTED RESISTORS— Hi-Stab. 

300 oft (5%.'/, .1. I watt, worth £3) 15 - 

• SELECTED COMPONENTS-Over 100 
Hi Stabs. Capacitors, Pots, Rectifiers, 
Switches etc 10/- 

• TRANSISTORS— Matched Output Kit: 

OC81D and 2-OC81 9/6 

R.F. Kit: OC44 and 2-OC45 9/6 

OC44, 45. 70, 72, 81 and 81 D Equivalents, 
each 3/- 

• CAPACITORS— Miniature Polyester Foil: 
160 VDC/100 VAC. 

33 pF to -1(iF:5 off, one preferred value. . 3/6 

•15jiF to 47u.F:5 off, one value S/- 

(P. & P. 1/6 per order, C.W.O.) 

ELMBRIDGE INSTRUMENTS LTD. 

Island Farm Avenue, West Molesey, Surrey 



TRANSISTORS 
and COMPONENTS 

Transistors and Components. OC71, OC72, 
OC44. OC45. OC81, OC81D, 3/- ea. OC83 6/--4d. 
P.P. Any quantity. AF116. AF11T. OC170. AF115. 
3/6. P.P. 

Silicon Rectifiers. BY100 (Branded) 800 P.I.V. 
550 M/A. Suitable for T.V., Radio etc.. 5/ — 4d. 
P.P. BYZ13. 200 P.I.V. 6 amps. 5/4. P.P. BYZ15 
200 PJ.V. 40 amps. £2.17.0. P.P. BYZ15 200 P.I.V. 
5 amps. 6/6 ea. P.P. BYZ15 800 P.I.V. 400 M/A. 
4/--4d. P.P. 

Texas Transistors. 2N1302-ASY28. 6/6 ea. 
2G302 = GET872. 7/6 ea, 2G301 = GET873. 6/6 ea- 
2G339A-AC127. 2/6 ea. 2G374-OC75. 2/4 ea. 
GMO290 U.H.F. transistors cut of freq. 700 Mc s. 
19/6 ea. 

Milliard Transistors. ASY28. 8/6 ea. AC126. 
8/-. OC75. 8/-. AF186 Cut of freq. 800 Mc/s. 
27/6. OC73, 3/6 ea. 

Milliard Thyristors. BTY-79-400R 400 P.I.V. 
4.7 amps, £1.16.9. 

S.T.C. Transistors (Grade 1) BSY95A 10/6- 4d. 
P.P. Any quantity. 

Newmarket Transistors (Grade 1) NKT271. 8/-- 
NKT773. 10/-. NKT278. 8/6. NKT214, 6/6. NKT275, 
6/6. NKT224. 6/6. NKT27A (diode). 3/6. 

Acos Record Player. Cartridge replacement for 
Garrard. Collaro. B.S.R. with needles. 12/6-6d, 
P.P. Mazda ECC85 valves. 4/6- !d. P.P. ORP12. 
ORP60 Cadmium Sulphide. Light sensitive. 
7/9 ea. 

Special Offer 1-OC44. ^2-OC45. - 1-OC81D. 
-1-OA81. 2-OC81. 12/6 + 4d. P.P. 
LF60 Erase Head (Transistor Type) £2.10.0 
J watt Labgear (Grade 1) Resistors 5d. ea.-4d. 
P.P. Any quantity. 5 % I watt Hi Stability res.. 9d. 
ea. + 4d. P.P. Any quantity. (Mail Order only.) 

J. ROBINSON (Radio & TV) 

4 inGHCLIFFE ROAD. BLACKLIST 
-MANCHESTER 9 



POCKET SIZE 
Transistor Testers 

Tests Transistors in or out of set 
Test both P.N. P. and N.P.N. 
Price 30/- Battery and Post Free 

Persona/ shoppers we/come 

BROOK & HILL ELECTRONICS 
695/697 Seven Sisters Road. 

London, N.15 
(50 yds. from Wards Corner) 



RECEIVERS & COMPONENTS 

(continued) 



JOHN'S RADIO (Dept. B) 

OLD CO-OP, WHITEHALL ROAD, 
DRIGHLINGTON. BRADFORD 

EXCLUSIVE OFKER 
Radio Telephone Type T.R.101. MK 2 Medium Po» 




These nets cover the range of 2-8 mcs. in two 
switched bands, wring R.'T and C.W. incorporating 
netting control, internal speaker and internal P. I". 
For 12 volt B.C. supply a separate unit la available 
tu use this set from 800/990 V. A.C. 
A meter is used for checking tho set while in 
operation, using 13 valves, (3 EL32 In Una! trans- 
mitter output) transmitter automatically tunes to 
the same F.X. as receiver, which uses one R.F. and 
two I.F. stages, being extremely sensitive and 
selective. 

Each set supplied fnlly totted) complete with mike, 
headset, spare valves, handbook, in carton, brand 
new. £17.10.0. carr. 30/- 

{Manufaelitriiig price atonr roil around £100 each) 
These sets have been made to stand up to the hardest 
of wear and working conditions. 
T.E. 101 MK 1 R/T M.C.W.. C.W. 
This set is practically Identical to the above, but 
being an earlier version, using: 
11 valves (one large valve In final output instead of 
three). Main difference external powor unit for 200; 
SS0 V.A.C. or 12 V.D.C., or 12 and 24 V.D.C. Also 
no Internal Speaker. Size of Mk. 1 and 2 approx. 
18 x 8 x 12 Ins.. supplied complete with mike and 
headset, handbook, fullv tested in carton, BRAND 
SEW. Set with m.-.iu- P.l". £14.10.0. 12 and 24 
V.D.C. £12.10.0. IS v.D.c. £10.10.0. Carriage all 30'-. 



STELLA NINE 
RANGE 

A new range of instrument cases 
including most of the designs used in 
Practical Wireless and Practical Elec- 
tronics, from September 1966 issues. 

These will be made for stock, ready 
for return-of-post service. 

Send now for free photostats and 
price lists. 

Money back guarantee on all goods 
if not satisfactory. 

E. R. Nicholls 

46 Lowfield Road, Stockport, 
Cheshire. 



RECEIVERS & COMPONENTS 

(continued) 

'BY 100 rectifiers 4- each anv quantity. Post 
Paid. BLAKE, 52A Runcorn Road, Bir- 
mingham 12. 



R & R RADIO & TV SERVICE 










Dept. 


P.W. 










MARKET STREET. BACDP. LANCS. 










releph 


me 465 








SALVAGE VALVES 




Tested before despatch 


SFia 


4/6 


U329 


5/- 


30PL1 


4/- 


2IIIM 




.11. is 


4/8 


10P14 


b/- 


PL3II 


6/- 


PCC34 


u- 


Kl "(I 


1/B 


20P5 


6/6 


PLS2 


H/H 


PY81 


Kffl 




»/- 


SOP 




0801 




C301 




ECL80 


8/6 


6FI5 


5/- 


10F1 


1/8 


I0P13 


Sffi 


30FS 


o/- 


EB91 


1/- 


30FL1 




20D1 




Pt TOO 


4/- 


EFS8 


6/- 


PT8S 


e/- 


30P12 


w- 


PL81 


!>/- 


B/30LS 




ril -JUT 


5/- 






PZ30 


w- 


20P3 


e/- 


ky- 


4/- 






Speaker 


. Bx.T.V. Ha. 


round 


•> x 4in., 


3/6: Kin. round 6/-; 


l«'.t 'J 

















Line Output Translotmers available, .state set model So 

Turret Tuners, 8/-. post 2 -. 

Soan Coils, etc Quote set model No. with all enquiries 
and S.A.E. for prompt reply. All goods subject to satis- 
faction or money refunded. 



MARCONI CANADIAN RECEIVER No. 52 
WMiaMB a i Shlppini 




tfa] 



cry- 
cali- 




brator, employing dual crystal to provide marker 
cheek at 10-100-1000 kc/s. One UK and two IF 
stage*. Other refinement-: valve, HT, and Signal 
check meter. Internal Sin. speaker and two H/ 
Phone ..input* with switched control. FR-AF 
l.imiter. Filter, BKO. II. t.rndyne pitch 
control. Wide and Narrow Bandwidth Man. or 
AVC on CW 4 KT. Fast and Slow tuning with lock. 
Additional OSC Tuning (plus A minus). Size 
13 X 14 x 12in. Fully tested and working. A.C. 
Mains 200.1240V. £14. Carr. £1. 
No. 52 GROUND-STATION comprising Receiver, 
Transmitter and 12v. D.C. Power Unit, £87.10.0. 
Carr. £2.10.0. (Maiuland only). 

NATIONAL H.R.0. SENIOR RECEIVERS 
5T MODEL 

■ nt tested 
condition. Complete 
with 9 coils SO Kc/s- 
30 Mc/s and Power 
Unit. *31.10.0. Carr. 
30 -. 

REJECTOR UNITS 1 .2-10 Mc/s 

Switched, 4 ranges. Primarily 
designed as station rejector i<>r 
R.C. Suitable for harmonic 
suppression and many other 
uses with slight alteration. 
Tuning dial with lock. Aerial 
in arul out sockets. Brand 
New 26/-. P. * P. 5 -. 

4 VALVE 4 WATT AMPLIFIER 

"C" Core transformers 
A.C. Mains 1 10/230 volts 



'300 ohms of high imped- 
ance Input. Output 3 or 
choice) 
i ..iitr..!-: On Oft switch. 
<:.tin control. Indicator 
light. Valve m-pectmu panel. 19 i7l Tin. Brand 
New in maker's carton. 79/8. Carr. 10/-. 

32ft. TELESCOPIC AERIAL MASTS 

Comprising 20ft 4 section tubular steel telescopic 
mast and 18ft. folding whip: Cm be erected In less 
than o minutes. Closes to 5ft. 9in. Weight 21 lbs. 
Must have cost well over £20. Price 67/8. P. & P. 7/6. 
ROTARY TRANSFORMER. 12v. Of. input, 250v. 
D.C. output at 125 mA. Size 3J x r,}ln. Brand new 
17/6. I', .v P. 67-. 

Also AMERICAN DYNAMOTOR UNIT. I2v. D.C. 
input 240v. output, 150 watts approx. Suitable for 
Universal A.C./D.C. equipment. 48/-. Can. 5.'-. 
Many other to pea. 

R.F. ANTENNA TUNER tA.T.U.) Calibrated scale. 
Ideal 160s" 4ii metres. Limited number onhr. 
Brand new with instruct hm'. 17/6. I'. A P. 7/6. 
ALL IS SETS & PARTS AVAILABLE 
' 'miioletv list <_■! 'ther bwgams. 1/-. 
S.A.E. all enquiries. Credit Terms Available. 

A. J. THOMPSON (Oept. P.W.) 

"EILING LODGE". CODICOTE. HTTCHIN, HERTS. 
Phone: CODICOTE 242 





793 



TAPE RECORDERS, TAPES, Etc. 



TAPES TO DISC— using finest professional 
equipment 45 rpm — 18/-. S.A.E. leaflet. 
DEROY, High Bank, Hawk Street. Carnforth. 
Lanes. 



SITUATIONS VACANT 



RADIO & TV Exam, and Courses by 
Britain's finest Home-study School. Coaching 
for Brit.I.R.E., City & Guilds Amateur's 
Licence, R.T.E.B., P.M.G. Cert., etc. FREE 
brochure from BRITISH NATIONAL RADIO 
SCHOOL, Russell Street, Reading. 



ALDERMASTON COURT POSTAL TRAIN- 

ING for B.Sc. (Eng) Part 1., A.M.I.E.R.E., 
A.M.S.E., City & Guilds, G.C.E., etc. prepares 
you privately for high pay and security as 
Technician or Technologist. Thousands of 
passes. For details of Exams & Courses in all 
branches of Engineering, Building, Electronics, 
etc. (including latest information on C.Eng.), 
write for 132-page handbook — FREE. Please 
state interest. BRITISH INSTITUTE OF 
ENGINEERING TECHNOLOGY, (Dept. 
169K), Alder mast on Court, Aldermaston, 
Berks. 



TV and Radio, City & Guilds, R.T.E.B., 
Certs., etc. on 'Satisfaction or Refund of Fee' 
terms. Thousands of passes. For full details of 
exams and home training Courses (including 
practical equipment) in all branches of Radio, 
TV, Electronics, etc. write for 132-page 
handbook — FREE. Please state subject. 
BRITISH INSTITUTE OF ENGINEERING 
TECHNOLOGY. (Dept. 137K), Aldermaston 
Court, Aldermaston, Berks. 



RADIO TECHNICIANS 

A number of suitably qualified candidates 
are required for permanent and pensionable 
employment in various parts of the UK, 
including London, but primarily Cheltenham. 
There are also opportunities for service abroad. 

Applicants must be 19 or over and be 
familiar with the use of Test Gear. They must 
have had Radio/Electronic workshop experi- 
ence and offer at least "0" level GCE passes 
in English Language, Maths and/or Physics, 
or hold the City and Guilds Telecommuni- 
cations Technician Intermediate Certificate 
or equivalent technical qualifications. 

Pay according to age, e.g. at 19 £747, 
at 25 £962 (highest age pay on entry) 
rising by four annual increments to £1,104. 

Prospects of promotion to grades in 
salary range £1,032-£1,691 There are a 
few posts carrying higher salaries. 

Annual Leave allowance of 3 weeks 
3 days, rising to 4 weeks 2 days. 

Normal Civil Service sick leave regulations 
apply. 

Application forms available from: 
Recruitment Officer (RT/37) 
Government Communications 
Headquarters 
Oakley. Priors Road 
CHELTENHAM, Glos. 



SITUATIONS VACANT 

(continued) 



G.E.C. HAMMERSMITH 

require 

TRAINEE ENGINEERS 

(ELECTRICAL or MECHANICAL) 

to work on the development and pro- 
duction of the most modern micro- 
wave tubes. Selected applicants will 
work initially in our Research Labora- 
tories at Wembley and will be trained 
in the techniques of microwave tube 
manufacture. Eventually, they will 
form part of a team producing these 
devices in our Hammersmith factory. 

Age 18-24 years. 

Candidates should preferably be study- 
ing for O.N.C. or equivalent and have 
some experience in industry or should 
have an 'A' level science subject but 
consideration would be given to a 
school leaver with a good basic educa- 
tion who had a practical bent. 

Please apply: Personnel Officer 

M.O. VALVE CO. LTD. 

Brook Green Works 

Hammersmith, W.6 

Telephone No. 603-3431 




SUPPLIERS OF 
ELECTRONIC 
EQUIPMENT 
^s TO . . . 

* UNIVERSITIES 

* COLLEGES OF TECHNOLOGY 

* COLLEGES OF FURTHER 
EDUCATION & SCHOOLS 

* ALL RADIO ENTHUSIASTS 
OFFICIAL SUPPLIERS TO MANY 

EDUCATION AUTHORITIES 
Usual Educational Discounts 



OUR NEW 1966/67 

illustrated catalogue 

NOW AVAILABLE 

(send 1 /- in stamps 
for your copy) 



INCLUDES 

Valves, Transistors, Transformers, Loud- 
speakers, Recording Tape, Coils, Resistors, 
Condensers, Potentiometers, Chassis, Recti- 
fiers, Test meters. Microphones, Tools, 
Solder etc. 

ALPHA RADIO SUPPLY CO 

1 03 Leeds Terrace, 

Wintoun Street, Leeds 7 

Telephone 25187 





i 



EQUIPMENT CABINETS 
OF DISTINCTION 

lllll'IIHIIIlllllllllllllllllllllllllllllllllllllllllllli' 




Imperial 

piiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiirl 

• Illustrated In this advertisement are 
two fine cabinets l'rom the Lewis 
Radio Range. 

• These cabinets are Just two of a 
really extensive range. 

EE • Each one carefully made by British 

— Craftsmen and soundly constructed 

= from the best materials available. 

E: • Fill in coupon below to obtain FREE 

B catalogue showing this wonderful 

range of cabinets. 

=?iiiiiim!mmmimiiiiiimiiiiiiiiiiiiiiiiiiiiiiimiiiiiiL- 




Lowflex 



lllllllllllllllh- 



rf0 



THE NEW LEWIS 
RADIO CATALOGUE 



Designed to assist your choice of 
Cabinet. 

The New Lewis Radio Cabinet Cata- 
logue — the most comprehensive ever 
prepared. Sent absolutely FREE! 
Please send your FREE cabinet catalogue. 

NAME 



ADDRESS 



Capitals please 



(Dept. P27) 




IN Chase Side, Southgate, London N.14. 
Tel.: Palmer's Green 3733/9666 



794 



ISIfftlrtMMM 



RADIO & ELECTRONIC 
CONSTRUCTION SYSTEM 



ABSORBING 

and 

EXCITING! 



I'nlmie and brilliantly simple. Hundreds of educational establish- 
ments— rniversities, 1'echnieal Colleges, Schools, the Armed Forces — 
are already using Itadionic for electronic instruction. Enthusiastic 
owners range from 9 to Hi years of age. 

Selected by the Council of Industrial Design for all British Design 
( 'i-iil n-s. Featured In Sound and Television broadcasts. 
The system is beautifully engineered from top quality British components. No 
soldering-. No mains. No prior knowledge needed. Simply arrange components 
on perforated transparent panel, position brass connecting strip underneath 
fix with 6BA nuts and circuit works with full efficiency. You can then dis- 
mantle and build another circuit. Your results are guaranteed by our 
Technical Department and News Letter Service. All parts available 
separately for conversion or expansion of sets. 

NEW! Our "No soldering" printed circuit board for superliet portable. 
Simply insert components and tighten nuts. 
No. ! Set £5.18.6 14 Circuits (Earphone) 
No. S Set £6.19.5 SO Circuits (Earphone) 
No. 3 Set £11.2.7 22 Circuits (7 x 41n. Loudspeaker output) 
No. 4 Set £15.3.8 26 Circuits (include 6 Transistor and refle 
Prices (Post Free) 



reflex superhets) 



(Plus P.T. Increases of 1/8: 1/11: 3/1: 4/2d respectively.) 
Full details from: 

RADIONIC PRODUCTS LIMITED 

STEPHENSON WAY, THREE BRIDGES 

CRAWLEY, SUSSEX 

Tel. CRAWLEY 27028 (Trade Enquiries invited) 




A No. 4 SET and 6-TRANSISTOR SUPERHET 




1 ESsSf 

Theoretical Circuit Practical Layout 

Our '£" Series of basic electronic circuits is available separately. Send 

for details of EI508 our do-it-yourself computer 



NEW RANGE U.H.F. AERIALS FOR 
BBC 2 (625) line transmissions 

All U.H.F. aerials now fitted with tilting 
bracket and 4 element grid reflectors. 
Loft Mounting Arrays, 7 element. 35/-. 
11 element. 42/6. n element, 50/-. 18 
element, 57/6. Wall Mounting with 
Cranked Arm, 7 element, 60/-. 11 element. 
67/-. 14 element. 75/-. 18 element. 82/6. 
.Mast Mounting with 21n. clamp. 7 element, 
42/6: 11 element. 55/-: 14 element, 62/-: 18 
element. 70/-. Chimney Mounting Arrays, 
Complete, 7 element. 72/6: 11 element. 80/-: 
14 element. 87/6; 18 element. 95/-. Complete 
assembly instructions with every unit. 
Low Loss Cable, 1/6 yd. C.n.F. Preamps. 
from 75/-. State clearly channel number 
required on all orders. 

BBC ■ ITV - F.M. AERIALS 

BBC (Band 1). Telescopic 

loft. 21/-. External S/D. 

30/-. "H" £2.10.0 

ITV (Band 3). 3 Element 

loft array. 25/-. 5 element 

35/-. Wall mounting, 3 

element, 35/-. 5 element, 

45/-. 

Combined BBC/ITV, Loft 

1+3,41/3: 1+5. 48/9: Wall 

mounting 1-3. 56/3; 1+5, 

63/9: Chimney 1+3. 63/9: 

1 + 5. 71/3. 

VII F transistor pre-amps 

75/-. 

F.M. (Band 2). Loft S/D. 12/6, "H". 30/-, 3 

element. 52/6. External units available. 

Co-ax cable. 8d. yd. Co-ax plugs, 1/3. Outlet 

boxes, 4/6. Diplexer Crossover Boxes. 12/6. 

C.W.O. or C.O.D. P. & P. 5/-. Send 6d. stamps 

for illustrated lists. 

Quotations for special arrays available 
on request 

K.V.A. ELECTRONICS (Oept. P.W.) 

27 Central Parade, New Addington 

Surrey 

LOD 2266 



NEW EDITION 

RADIO VALVE 
DATA 

CHARACTERISTICS OF 7,000 VALVES 

TRANSISTORS • SEMICONDUCTOR 

DIODES AND RECTIFIERS •CATHODE 

RAY TUBES 

Compiled "WW" 8th edition. 9/6 

Postage 1 /- 

OUTLINE OF RADIO 

AND TELEVISION 

by J P. Hawker. 30/-. Postage 2/-. 

1966 WORLD RADIO 

TV HANDBOOK 

28/-. Postage 1/-. 

TRANSISTOR TRANSMITTERS FOR 

THE AMATEURS 

by D. L Stoner. 21/-. Postage 1/- 

TRANSISTOR POCKET BOOK 

by R. G. Hibberd. 25/-. Postage 1/-. 

RADIO CIRCUITS 

by W. E. Miller revised E. A. W. Spreadbury. 

25/-. Postage 1/-. 

RADIO AND TELEVISION 

TEST INSTRUMENTS 

by G. J King. 25/-. Postage 1/6. 

RADIO AND AUDIO 

SERVICING HANDBOOK 

by G. J. King. 25/-. Postage 1/6. 

THE MODERN BOOK CO. 

BRITAIN'S LARGEST STOCKISTS 

British and American Technical Books 

19-21 PRAED STREET 

LONDON, W.2 

Phone: PADdington 4185 
Closed Saturday 1 o'clock 



UirM!imi4i*E] 




£6/5/6 

.-•" Solve your communica- 
tion problems with this 
new 4-Station Transistor Intercom (1 master and 
3 Sabs). In de-luxe plastic cabinet* for desk or wall 
mounting, fall. talk listen from Master u> Snbs and 
Sobs la Master. Ideally suitable (or Business. Sur- 
gery. Schools. Hospital. Office and Home. Operates 
on one !>v battery. On/off switch. Volume control. 
Complete with 8 connecting wires each 66ft. and 
other accessories. P. A P. 6/8, 




Modernise business or home with this new two-way 
Portable Transistor Intercom. Consisting of Master 
and Sub. in strong plastic cabinets, with chromium 
stands. Designed as a two-way Instant communica- 
tion system. Call/talk/listen from Master to Sob and 
Sub to Master. Operates on one BV battery. 
Complete with 60ft. wire. Battery 2/6, P. 4 P. 2/6. 




Our Price Only 



Why not Ixiost business efficiency with this incredible 
De-luxe Telephone Amplifier. Take down long 
telephone messages or converse without holding the 
handset. A status symbol? Yes. but very useful one. 
On/off switch. Volume Control. Operates on one 
9V battery. P. A P. 2/6. Battery 2/6 extra. 
Full price refunded if returned in 7 days. 

WEST LONDON DIEECT SUPPLIES (PW/2) 
169 KENSINGTON HIGH STREET. LONDON. W8. 



795 











10/ 


BARGAIN 


SALE 10/- 


10/- 


PISTOL-GRIP SOLDERING IRON 




10/- 6 NPN or PNP Switching Transistors 




(USUALLY 25/-) 




(min. 200 mc/s) 


10/- 


20 well assorted TRANSISTOR 




10/- 10 Transistor Holders 




ELECTROLYTICS 




10/- ACOS MONO PICK-UP HEAD 


10/- 


3 Television Smoothing Condensers, 




COMPLETE WITH NEEDLES 




200/200/xf., 200/1 00uf.. 300/1 25/50/xf., 




10/- 3 Miniature earpieces complete with 




275 volt 




plug and lead 


10/- 


50 assorted i watt 5% Resistors 




10/- 20 Diodes. Very high quality 




(Long leads) 




10/- Magnetic Lapel Microphone with 


10/- 


1 00 J to ^ watt mixed resistor types, values 




plug and lead 


10/- 


100 -i to 3 watt Close Tolerance types 




10/- 3", 4" or 5" Low impedance LOUD- 


10/- 


100 Silver Mica/Ceramic/Polystyrene 




SPEAKER 




Condensers 




10/- SIGNAL INJECTOR R.F./I.F./A.F. 


10/- 


50 assorted paper condensers 001 to -5^f 




parts and circuit 


10/- 


100 miniature paper condensers 




10/- Car Rev. Counter, Parts and Circuit 




(Mixed values) 




(excl. meter) 


10/- 


50 untested TRANSISTORS 
(excellent value) 




10/- 12 pre-set potentiometers mixed 


10/- 


FREE! 10/- FREE! «„-.—'».». .,.-.. 


10/- FREE! 10/- FREE! 




' ANY ELEVEN ITEMS 


10/- 


FREE! 10/- FREE! 


10/- FREE! 10/- FREE! 




Hush your order now/ These prices cannot be repeated/ 




G. F. MILWARD 


17 Peel Close, Drayton Bassett, Nr. Tamworth. Staffs. Phone: TAMWORTH 2321 POST ONLY 




The TMNCH . . 
if o*t need I 

HOLE PUNCHES 

Instant Type 

g" diameter 6/10 ea 

Screw-up Type 

+1" diameter Toggle switch .. .. 8/6 .. 

86 ■■ 

1" „ B7G 9- „ 

|" ,. B8A. B9A 9/6 „ 

-U" 10,2 ,. 

J- 10 8 „ 

1- 11/8 „ 

14" diameter Int. Octal 13/4,, 

1J- 16 2 ,. 

1|- 1810.. 

i|* „ B9G 21* .. 

1J- 244 .. 

2^" ,. Meter 33 2 „ 

Complete Set £9.3.6. 

A/o extra charge for postage and packing 

in the U.K. 

Now supplied by 

TOMPKINS & LONGMAN LTD. 

237 GIPSY ROAD 
WEST NORWOOD, S.E.27 

Tel. Gipsy Hill 5000 



FIRST-CLASS RADIO 
AND T/V COURSES... 

GET A CERTIFICATE ! 



After brlel, Intensely interesting study 
—undertaken at home In your spare time — 
YOU can secure a recognised qualification 
or extend your knowledge of Radio and TV. 
Let us show you how. 



FREE GUIDE 



The New Free Guide contains 120 
pages ol Information of the greatest 
Importance to both the amateur and 
the man employed In the radio Industry. 
Chambers College provides first 
rate postal courses lor Radio Amateurs' 
Exam., R.T.E.B. Servicing Cert., C. 4 C. 
Telecoms., A.M.I. E.R.E. Guide also 
gives details of range of diploma 
courses in Radio/TV Servicing, Elec- 
tronics and other branches of engineer- 
ing, together with particulars of our 
remarkable terms ol 

Satisfaction or refund of fee 

Write now for your copy of this invaluable 
publication. It may welt prove to be 
the turning point In your career. 

FOUNDED 1885— OVER 
150.000 SUCCESSES 



CHAMBERS COLLEGE 

(Incorp. National Inst, ol Engineering) 

(Dept. B49F), 148 HOLBORN 
LONDON, E.C.I 



QUOTATIONS FOR COMPONENTS send 

your list of requirements for competitive 

quotation by return of post. 

HEAVY DUTY RELAYS 9-14v. DC coll, single 

pole, switching up to 40 amps at low voltage. 

2 6. P.P. 1 6d. Discounts for quantities. 
Hl-K CERAMIC CAPACITORS (DISC) 

500v. DC working. 1,000 pF 2/6 per dozen, 

P.P. 9d. 10.000 pF 3/9 per dozen. P.P. 9d. 
SUBMINIATURE ELECTROLYTICS 100 mfd. 

15v., brand new, at the fantaslic price ol 9 6d. 

per dozen. P.P. 9d. Send lor list ol other 

bargains. 
POTENTIOMETERS 5KO lin, lOKft lin 

100KQ lin, 250KH lin, 1MS2 log, 2Mfl log., 

2MQ lin. l/.each. P.P. 6d. 
With double pole switch 500KJ! Iln, 1M(2 log, 

2 -each. P.P. 6d. 
With single pole switch 10Kf) lin 50K<! Iln, 

2/- each. P.P. 6d. 
Pre-sets 250KS! Iln, 250KC2 log, 300KQ lin, 

2MS3 lin. 1M11 Iln. 1/- each. P.P.6d. 
FERROXCUBE TOROIDS Leaflet on complete 

range available on request. 
TOROID TRANSFORMERS for Inverter 

applications, etc. 20 watt version: 12v. Input, 

250v. SOmA output. 19/6. P.P. 4/6. 60 watt 

version: 12v. inpul, 300v. 200mA output. 

39.6. P.P. 5 -. Torold transformers also supplied 

to your requirements. 
RESISTOR PACKS 100 well assorted values 

and types, mainly Jw. hy-slabs, bul also some 

1,'IOw. 5w. 1w. 2w. 1 % to 10";.. A super buy al 

7,6. P.P. 1/6. 
CAPACITOR PACKS 100 well assorted silver 

micas, ceramics, polyesters, papers, electro- 

lytics, etc. 10/-. P.P. 1/6. 
VALVEHOLDERS B9A paxolin 2/- per dozen. 

P.P. 1 6. 
UX7 10 -per dozen. P.P. 2/6. 
HEADPHONES German made. 5 and 2.000 ohm 

versions. 20-. P.P. 2/-. 
TRANSISTOR BARGAINS send for complete 

lists. Quotation by return for any type of tran- 
sistor. 

BRIAN J. AYRES & CO. 

Dept. ED. 8 Hartfleld Road Wimbledon, 
London S.W.19 Telephone: Wimbledon 6063 



796 



^IMPRACTICAL- ^^ 

Boat Owner 

THE NEW MONTHLY ALL BOAT 
ENTHUSIASTS HAVE ALWAYS WANTED 




New and new in outlook, excitingly different from stem 
to stern. Practical BOAT OWNER has been expertly planned 
to give the maximum practical help to all boat enthusiasts, 
newcomers and old hands alike, up river and out to sea. 



Month by month Practical 
BOAT OWNER will advise on 
buying, building and main- 
taining sail and power craft. 
You'll learn about the latest 
equipment and materials. 
Step-by-step instructions on 
everything from minor repairs 
to major overhauls will help 
you keep your boat in trim 
for the lowest outlay. Experts 
will guide you to safer, better 
seamanship. 



FREE 

INSIDE! 

SKIPPERS' SAFETY 
CHECK CARDS 

Two waterproofed, handy- 
size cards to keep in the 
cockpit for instant check. 

1 THE RULE OF THE ROAD 

2 WARNING SIGNS & BEACONS 

More FREE cards in the following issues 




BUILDING A BOAT? Or hoping to? 
First of a series for non- experts 
that makes the job easy. 

FAMILIES AFLOAT. Children can be 
safe, snug and contented, says our 
woman's page writer . . . even tots in 
carrycots. 

TREAT YOUR OUTBOARD MOTOR 

RIGHT, a photo series on step-by- 
step care and maintenance. 

PLUS Gadgets to make. Buyer's 
Guide to essential equipment. New 
craft for family fun. Fire protection. 
New life for an old boat. Essential 
knots and hundreds of other 
practical tips. 



■ 'iv tsei 

wner 





797 



PRIC 



SPECIAL RADIO 
CHASSIS OFFERS 



HI-FI CONTINENTAL 
STEREOPHONIC RADIOGRAM CHASSIS 




Magnificent 'Continental' Stereophonic Radio- 
gram Chassis with piano key switches, built- 
in lerrite rod aerial. Comes complete with two 
10" elliptical loudspeakers, plus a mono/stereo 
4-speed automatic record changer. Complete 
29i gns. (Units available separately II required. 
Chassis only, 21 gns.). 

Special terms available of £10.6.6 deposit 
followed by II monthly payments of £1.7.3 
(total H.P. of £37.17.0) -15/- P. & P. Send 
£11.1.6 now. 



IMPERIAL HI-FI 
STEREOPHONIC RADIOGRAM CHASSIS 




The Imperial Stereophonic 4 waveband chassis 
has the most advanced specifications yet offered 
in this country. There is a built-in lerrite rod aerial, 
seven piano key buttons, controlling mono/sfereo 
selection. GramLong-Medium-Short-FM-ON/OFF. 
The unit comes complete with two 10" elliptical 
loudspeakers plus a mono/stereo 4 speed auto- 
matic record changer. Complete £41.9.6. 
Chassis only, 29: gns. 

Special terms available ol £13.16.6 deposit 
followed by 24 monthly payments of £1.8.10 
(total H.P. £48.8.6) l 17/6 P. & P. Send £14.14.0 
now. 



EMPRESS HI-FI . 
AM/FM STEREOPHONIC CHASSIS 




This most advanced radiogram chassis with 
automatic push button selection covers short, 
medium and long wavebands plus V.H.F./F.M. 
Offered complete with 2 10 x 6 speakers 4 speed 
Stereo/Mono autochanger only £35.19.6. Chassis 
only, 25i gns. Special terms available of £12 
deposit followed by 18 monthly payments of 
£1.11.7. (total H.P. £40.8.6)H5/- P. & P. 
Send £12.15.0 now. 

All Lewis Radio equipment including valves 
aref ully guaranteed for one year free of charge. 
Send your cheque or P.O. today while stocks 
last to Dept. P.27. 



LEWIS 



radio 



LEWIS RADIO, 100.CHASE SIDE, SOUTHGATE 
LONDON, N.14. Telephone: PAL 3733/9666 



PADGETTS RADIO STORE 

OLD TOWN HALL 

LIVERSEDGE. YORKSHIRE 

Telephone: Cleckheaton 2866 

Special Offer. Garrard Record Players. __ 

Auto Changers. Model AT6 £8.2.6. Model 1,000 

£5.12.0. 

Simile Player. Model S.P.25 £8.2.6. Carriage 

and Insurance on any Model 10/-. AH complete 

with cartridge and maker's guarantee. 

19 Set with outer case. Receiver section 

complete with valves. 

Parts Removed. 500 micro-amp meter, all 

transmitter parts. Relay and 807 valve. 

Condition fair. No dry rot 10/-. Carr. 10/-. 

Reclaimed Tubes. Six months' guarantee. 

AW43/80. 30/-. MW43/80, 30/-. MW43/69. 30/-. 

CRM172. 30/-. CRM142, 17/-. 12in. Tubes 10/-. 

171n. Tubes perfect but without guarantee. 

17/- each. Carriage on any Tubes in G.B. 10/-. 

Specially Selected Nearly New Valves. 

6 months' guarantee. 







ARP12 


1/6 


EL38 


5/- 






ESGL80 


3/6 


5U49 


4/- 


PCF80 


5/6 


ECC83 


5/- 


6K7 


1/» 






ECC82 


4/3 




1/9 


807 


51- 


EF91 


21- 


185BT 


8/6 


Single Valves. 


Post 7d. 












VALVE LIST 






Ex. Equipment. t 


niontha 


guarantee. 


Single Valves. 


Post 7d. 












PCF80 


2/- 


10P13 


2/6 






PCC84 


21- 


10P1G 


hl- 






PCL82 


4/- 




iil- 






PCL83 


3/- 




o/- 






PCL85 


3/- 


201' 1 


4/- 






PZ30 


5/- 




K/ti 






PY81 


1/6 


U329 


tu- 






PY82 


1/6 




rn 






PL81 


4/- 










PL36 


5/- 


U191 


51- 






PY33 


5/- 










6B8 


1/6 


U282 


b/- 


6U4 


51- 


6F1 


1/- 




&/- 






6F14 


5/- 






KT36 


51- 


10C2 


5/- 







Breaking up 19 Sets. 

Relays 100 Ohm Coil 21-. Post 2/6. 1 Doz. 26/-. 

Post Paid. Jack Sockets 7/6 doz. Post Paid. 

Toggle Switches 7/6 doz. Post Paid. 

Pointer Knobs 7/6 doz. Post Paid. 

Top Grade Diodes 3/6 doz. Post Paid. No duds. 

Perfect Speakers. Removed from TV sets. 

Goodmans 7x4, 5/-. Goodmans 8x5. 7/6. 6x4 

and 5ins., 3/-. Plus Post on any Speaker, 4/-. 

New 12 inch Speakers, with ouilt-in tweeter, 

28/6, 3 or 15 ohm. Coil. 28/6. Post Paid. 

New 24 volt Miniature Model Makers Motor 

will run from 6 volts. 6/6. Post Paid. Motors 

Single Phase Quarter H.P., 26/-. Sixth H.P., 

Ex Washing Machines. Fully guaranteed 
Plus Carriage 10/-. _ _, 

Type 46 Set. Complete with valves. Send receive 
switch removed, 12/6. Post Paid. 



N EW VALVES ! 

Guaranteed Set Tested 
24-HOUR SERVICE 







DF90 


Mil 


EF80 


4/3 


rias 8/3 




Rf» 


DK3-J 


11- 


EF85 


6/- 


PY33 8/3 






DK91 


*l- 


EF86 


6/- 








DK96 


w 


EF89 


4/9 


PY81 5/- 






DL33 


6/H 


EL33 


ti/3 






7/9 


DL35 


4/9 


EL41 


8/- 


PY83 5/3 






DL92 


4/3 


EL84 


4/3 






8/3 


DL94 


5/- 


EY51 


o/ll 


B19 6/6 






DL90 


Mll 


EY86 


Wit 








DY8B 


Hf« 


EZ40 


U8 


U26 8/6 






DY87 


6/3 


BZ80 


3(8 


U191 10/- 




5/K 


EABC30 5/6 


EZ81 


4/- 


U301 11/6 






RAF49. 


<7- 


BZ32 










EBC41 


6/6 


KT61 


6(3 


UABCS0 5/- 






EBF80 


.•>'» 


S78 










EBF89 


5/9 


PCC84 


5(8 


UBC41 6/6 






ECC81 


3(3 


PCC89 


9/9 


UBF89 5/9 






ECC82 


4J6 


PCF80 










ECC83 


4/6 


PCK82 


5(9 


TJ0H4S 8/6 






BOOM 


5/8 


PCL82 


6(3 


UCH81 5/9 






ECH35 


5/9 


PCL83 










ECH42 


8/fl 


PCL84 


7/3 


UCL8S 8/6 






ECHSl 


Si- 


PCL85 


7/9 


UF41 7/9 






ECLS0 


bil) 


PL36 






3/9 


ECUS 


si- 


PL81 






El'I.-'i 


va 


PL82 








EF39 


3/H 


PL83 


5/11 UY41 4/9 


DF91 


2/9 


EFJ1 


5/9 


PL84 


6/- 1 UY85 4/9 


Postage on 1 valve 9d. extra. On 2 valves or more. 






extra. Anv parcel injured aRainst 


damage in transit 6d. extra. Office 


address, no callers. 


GERALD BERNARD 




83 OSBALDESTON 


ROAD 




STOKE NEWINGTON 






LONDC 


)N N.16 





SHORT-WAVE 
KITS 



H.A.C. 

NEW RELEASE: MODEL "DX" 




Famous for over 30 years for 3hort-Wave Equip- 
ment of quality, "H.A.C." wore the original 
suppliers of Short-Wave Receiver Kits for the 
amateur constructor. Over 10,000 satisfied 
customers — including Technical Colleges, Hos- 
pitals, Public Schools. K.A.F.. Army. Hams. etc. 

IMPROVED 1967 RANGE 
One-valve model "DX". complete kit— price 56/6 
(Post 3/0). 

Customers sav: ".Definitely the beat one-valve 
8. W. Kit available at any price." This kit contains 
all genuine short-wave components, drilled 
chassis, valve, accessories and full Instructions. 
Ready to assemble, and of course, aa all our 
products — fully guaranteed. Full range of other 
klU still available, including the famous model 
"K". Before ordering, call and Inspect an assembled 
receiver,— or send /or a descriptive catalogue and 
order form to: — 

"H.A.C." SHORT-WAVE PRODUCTS 
29 Old Bond Street, London W.I 



SLEEP LEARNING 

Make use of your tape recorder lo learn scripts, 
languages, songs, speeches etc. etc. the modern 
way. . 

Send S.A.E. for details and price list of time 
switches, pillow speakers, tapes and complete 
sleep learning outfits 

MAINS POWER PACKS 

The ideal economical and safe way of running 
any Transistor Radio, Record Player, Tape 
Recorder, Amplifier etc. from A.C. Mains. 
The MAJOR "Power Plus" for 9v.; qq/c 
6v.; 4Av.; Single Output. P. & P. 2/6 OO/O 
For 9v. + 9v.; 6v. + 6v.; 4£v. + H") If* 
4iv. Two separate outputs. P. & P. 2/6 *»«£/ U 
Please stale outputs required 
The BIJOU " Power Plus". For the smaller 
set using PP3 type battery. Supplied complete 
with special adaptor enabling you to reactivate 
your existing PP3 type battery. 1 7 /R 

P. & P. 2/6 l '/° 

All units are completely isolated from mains by 
double wound transformer ensuring 100% 
safety. 

LISTEN TO THE WORLD on TELSTAR our 

1 -VALVE 

SHORT WAVE 

RADIO 

Receives speech 
and music from 
all over the 
world. Price includes valve and one coil covering 
40-100 metres. Can be extended to cover 10-100 
metres. Can be converted to 2 or 3 valve and all- 
mains speaker use. *IR/- „ „_ „, 
Total building costs °'*i P. & P- */- 
All parts available separately. 

R.C.S. PRODUCTS (RADIO) LTD. 

(Dept. P.W.). 11 Oliver Road, London, E.17 




798 



- ■*^^^^' 




(12) 



(9) POWER AMPLIFIERS. 10 watts 

RMS output. 100m V input. 30 c/s to 20 k/cs 
— IdB. 6-Translstor Push-pull. Panel size 
4 x 2| X 1 in. H/S 4 x 4ln. 
TPA10/3 3-5 ohm spkr. £4.10.0, pp. 2/6. 
TPA10/15 12-16 ohm spkr. £5.5.0. p.p. 2/6 
(Mains unit 1 or 2 amplifier s, 59/6, p.p. 2/6) 
The Finest High Fidelityat j 

Unbeatable Prices 




10 AND 20 WATT MONO AND STEREO TRANSISTOR AMPLIFIERS 



25 W ATT AMPL IFIER 

8-Transistor design. Push-pull output 
tor 7J to 16 ohm speaker. 150mV Input. 
30c sto20k.<cs — 1dB. Forusewith valve or 
sistor pre-ampliflers as item (10) above 
PRICE BUILT p-i 4qa p.p. 

AND TESTED I./. 19.0 3/. 

(Mains unit 79/6, p.p. 2/6) 



(13) MULTI-METERS SCOPE 
PT34 1kV 39/6 EP30k 30kV £6.10.0 
TP10 2kV 75/- EP50k 50kV £8.15.0 
1T1-2 20kV 69/6 500 30kV £8.17.6 

TP5S20kV £5.19.6 EP100k100kV £10.10.0 
• CT52 Scopes £22.10.0 P.P. 10/- 
Complete range of test equipment in stock 



(16) NOMBREX TEST UNITS 

* 150 kc/s — 350 mc.'s RF Generator 
£10.10.0. All Transistor. 

* 10 c/s— 100 kc/s Transistor. £16.19.6 
Audio Generator. 



HENRY'S RADIO LTD. 

303 EDGWARE RO„ LONDON, W. 

PADdington 1008/9 (STD 01-723-1008) 

Open Mon. to Sat. 9-6. Thurs. 1 p.m. 

Open all day Saturday 



(15) GARRARD BATTERY 
2-SPEED TAPE DECK 

Brand New with R/P head, 
erase/osc. head, tape cassette 
Specifications and osc. cir- 
cuits. 2 speed 2-track 9 volt 
operated. List Price 13 gns. 

PRICE £8.19.0 ' 3/5 

COMPONENTS AND 
EQUIPMENT. The largest 
range in the country. 7,6 p. 1/- 
buys 1967 200-page catalogue 
with discount vouchers. 



(10) PREAMPLIFIERS. 8 input selector. 

Treble, bass, volume, filter controls. 

1jmV to lOOmV Inputs. Battery operated 

or from Mains Unit. Output up to 150mV 

RMS. 

MP2 Mono 9i X 2\ x 2in. £5.10.0. p.p. 2/6 

(grey and gold front panel 8/6). 

SP4 Mono/Stereo, 9 x 3} x Ifin. £10.19.6, 

p.p. 3/6 (front panel plate 12/6) 

# ALL UNITS BUILT AND TESTED 



(12) MW LW QUALITY 

TRANSISTOR RADIO TUNER 

Fully tunable superhet with excellent 
sensitivity and selectivity. Output up 10 
s volt peak. Complete with front panel, 
etc. 9 volt operated. For use with any 
amplifier or tape recorder. 
TOTAL COST fO 1 Q C P.P. 

TO BUILD 1-0.13.0 o tl 

(14) VHF FM TUNER ^ 

Supplied as 2 Preassembled Panels, plus 
metal work Superhet design. 88-108 Mc.'s. 
9 vo't operated. 6 Mullard Transistors. 
Total cost to assemble £12.17.6, p.p. 2 6 

STABILISED POWER SUPPLY 

Two outputs. 3.6 volt and 9.6 volt up to 
250mA each. Transistorised and tuner 
stabilised. 110 to 250 volt mains input in 
case with leads. PRICE 67;6, p.p. 2/6. 



(17) 5 WATT AMPLIFIER 

6- Transistor Push-pull, 3 ohms. 6mV into 

1K. 12/18V supply, 2J x 2 x 1Jin. 

BUILT AND TESTED CQ /C P.P. 

(optional mains units 54.'-) DSJ/O 2,. 

1j watt version 59 6. 

Matching Preamplifier, 6 inputs, treble, 

bass/selector/volume controls. 6-10mV 

o/put. 9-18V supply. 79 6, p.p. 2/-. 

For use with any Transistor Amplifier 



SEE BACK COVER FOR MORE ITEMS OF INTEREST 



FMT41 FM TUNER. 6-transistor 
3 diode design. Com-rn in fip.p. 
pletely built and tested*-!). lU.U 2/. 
(19) AMT31. Med. Wave Tuner Built 
ready to use. 79/6, p.p. 2/-. 




FDCErO AMBITIOUS ENGINEERS 
I m ■■! ■■ -™ E LATEST EDITION OF ENGINEERING OPPORTUNITIES 



Have you sent for your copy? 

ENGINEERING OPPORTUNITIES is a 
highly informative 132-page guide to the best 
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all branches of Engineering. This unique book 
also gives full details of the Practical Radio 
and Electronic Courses, administered by our 
Specialist Electronics Training Division — the 
B.l.E.T. School of Electronics, explains the 
benefits of our Appointments Dept. and shows 
you how to qualify for five years promotion 



in one year. 



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PET SUBJECT 

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BRITISH INSTITUTE OF ENGINEERING 

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THE B.l.E.T. 



PRACTICAL 
EQUIPMENT 

Basic Practical and Theoretic 

Courses for beginners in 

Radio, T.V., Electronics, etc. 

A.M.I.E.R.E., City & Guilds 

Radio Amateur's Exam 

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Practical Radio 

Radio & Television Servicing 

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POWEK DNTTS TYPE 234 

19In. rack mounting fnlly smoothed and (used tor 230v. 

A.C. input. H.T. output adjustable from 180 v. to 270 v. 

at 80mA, by means of primary taps and high-low switch 

in the secondary winding. L.T. output 0.3 v. AC. ;i t. 4 

amps. Fitted with M.I meter to read A.C. input and D.C. 

output i 

£3.19.6. 

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Packing and carriage 15/-. 



Second-hand, tested, in good conditiun 



HEADPHONES 

DLR5, Low Impedance, balanced armature. Earpieces 

can be used as sound powered Microphone, 10/-. 

No. 10 Assembly. Moving Coil Headphones with moving 

coil Hand Microphone litted with prcss-to-talk switch. 

Rubber carpada. Cord terminated with army type fi-polnl 

moulded connector. Low impedance. Brand new. 20/- ™. 

Small quantity available ii second hand meHU>Be(i 

checked, in perfect order. 8/8 ea. 1*. & P. 3/0 per set. 



EADIO FREQUENCY THERMOCOUPLE METERS 

Scaled to 1 AMP, 2Jln. round projecting 18/6 

Packing and postage 2/6 per order. 

21" SCBEEN CATHODE BAYTUBES 
UG7-5 General Purpose, Green medium persistence tube. 
Double electrostatic deflection, for symmetrical deflection 
onlv. Typical EHT-800v. Focus voltage 2OO-3O0V. 
Deflection sensitivity X-0.13 to O.I9mm.v.; Y-0.21 to 
0.28mm/v. Base B9G. 

DG7-6 — identical with DG7-5 but with X' plat, - 
intended ior asvmmctrical deflection only, 80/-. Suitable 
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MULTIMETERS 




Hoi 



5J x 



TYPE MF15 

A.C and D.C voltage ranges: 

0-10-8O-25O-6OO-I000V. 
D.C. eurrciU ranges: 
ftOO|xA10-100mA. 
Kesistunce ranges: 100MO-1MQ. 
The meter Iv also calibrated tor 
Inductance (1O-1O00H), capacity 
(O.fiaF) and output level measure- 
inuiits. Sensitivity 2000S1V. 

Accura<:y ±2.5% for D.C. and 
±4% for A.C. nioaauremeii'.-. 
3j x i;in. Price £3.3.0. 



Type 108-IT: 24 range precision portable meter. 5000 
,,'p.v. D.O. Volte: 2..l-l0-5(i-25()-5i|ii-2f.ii(iY. A.C. Volts: 
1 0-50-1 00-200-500-2500V ; D.C. current 0.6-5-50-500mA 
Resistance 2000-20.0"n „hni»; 2-2H megohms. Power 
output calibration In A.C. (or 000 ohms line. Complete 
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PLES8EY ELECTROLYTIC CAPACITORS 

24U.Fat27BV .... 2/- 100-400|iF at 275 V 3/8 

200U F at 275 V. . . . 8/6 1 00-20-5-25 |XF (100- 

20-"0uFat 450 V... 8/- a' 350 V: Buf at 

:,o loojiF at 275 V. 8/- 50 V. BfluF at 23 \ ) 3/6 

All voltages nre D.O, working. Postage B/- per order. 



Our new price list ol Valves. Tubes and Semiconductors is 
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typos it is a useful relerenoe work divine: Valve and Tube 
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Ray Tubes and Semiconductors. Send S.A.E. lloolsoapl 
now to get your copy tree of charte 



ZENER DIODES 
250m W 5%: 

BZ VI 1,00.0V .. 
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OAZ203, 0.2V 
280m W 15%: 

OAZ208, 4.3V . . 

OAZ209, 4.7 V . . 

OAZ210, 0.2V . . 
8.85 10% : 

V 11425 B (4.96V) 

VR475B (4.75V) 
5.25W10",,: 

VR7AI7.0V) 

VHllA(ll.OV) .. 
7.0W5%: 

OAZ222 (5.6V) . . 



6/6 BZY13, 80.0V 



10/- 
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71- 
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6/6 
6/6 
6/- 

6/6 
6/6 

8/- 
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OAZ211. 7.5V 
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OAZ213, 12.0V 

VK575B (5.75V) 



VR13A (13.0V) 
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6/6 

71- 
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9/8 

6/- 
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6/6 

6/0 



8/- 
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FERRAMI TBANSISTOBS 

ZT83 .. .. 12/- ZT152 

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54/- 
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TRAN3ISTOR CIRCUIT COMPONENTS 

Variable Twin liana Miniature Tuning Capacitor, 
two section. 4-165pF. anil 3-65pF. with l-8pF 
trimmer, complete with Broadcast Band Oscil- 
lator Coll -• 8 ' 8 

WEYRAD RA2W FEBRITE HOD AERIAL, 

l.W (1TW winding with Car Aerial Coupling 12/8 

P50/1AC OSCILLATOR COIL, MW/LW 5/4 

P50/2CC, 470 kc/s., 1st and 2nd l.F 5/7 

.470 kc/s., 3rd I.F.: 6/- 

OSMOB Subniiniaturc- Transformer for Mains-to- 
Transistor supply conversion. Type MT9, Output 
9-0-9 v. ateOmA 10{- 

SultaMe Germanium Diode BJ7B »/•» 

Packina and imstagc 9/- per order. 



800 



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The Strand Amplifier 
The PW Signal Generator 

The Berkeley Loudspeaker Enclo 

sure 

The Luxembourg Tuner 

The PW Troubadour 
The PW Everest Tuner 

The PW Britannic Two . . 
The PW Mercury Six 

Beginner's Short Wave Two 
S.W. Listener's Guide 

Beginner's 10-watt Transmitter 
Transmitting and Aerial Data 

PW "Sixteen" Multirange Meter 
Test Meter Applications Chart 



} 



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(Oct. 1 962) 51- 

(Dec. 1962) 5/- 

(June1962) 7/6 

(May 1962) 6/- 

(Nov. 1963) 5/- 

(Dec. 1963) 5/- 

(Jan. 1964) 5/- 



The Celeste 7-transistor Portable "1 

Radio [ (June 1963) 51- 

The Spinette Record Player 



Transistor Radio Mains Unit 
7 Mc/s Transceiver 



'\ (June 1964) 5/- 



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The PT Multimeter (October 1961) PT .. .. 5/- 

The Beginner's Short Wave Superhet (Dec. 1 964) 5/- 

The Empire 7 Three-band Receiver (May 1965) . . 51- 

Electronic Hawaiian Guitar (June 1965) . . . . 51- 

Progressive SW Superhet (February 1966) .. 5/- 



Beginners' 5-Band Receiver 
Home Intercom Unit 



::} 



(Dec. 1966) 5/- 



PLEASE NOTE THAT WE CAN SUPPLY NO BLUEPRINTS OTHER THAN THOSE SHOWN IN 
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THE ONLY COMPLETE KIT AVAILABLE IN THE 
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SPECIFICATIONS: , 

TONE COLOURS (ROCKERTABS) 10 DIFFERENT TONES CAN BE SELECTED 

SWITCHED VIBRATO. • CABINET SIZE 30i x 15J x 9 in. • WEIGHT 35 lb. 

49 NOTE C-C FULLY SPRUNG KEYBOARD • 6 OCTAVES OF GENERATORS 

PRESET VOLUME CONTROL • TONE COLOUR BLEND CONTROL 

FOOT SWELL PEDAL • OUTPUT UP TO £ VOLT • 110/250 VOLT 

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mm 




FM STEREO DECODER 

7 Milliard Transistors. Printed 
Circuit Design with Stereo Indi- 
cator. For use with any valve or 
transistor FM. Uses pot cores to 
Milliard design and ger, and 
silicon transistors. . I 

Complete £5.19.6 r 



Kit Price 

Leaflet on request. 



2/- 



<- 



SEE PAGE 799 FOR 
MORE ADVERTS 



TUNNEL DIODES 

1mA 22/6; 5mA 15/-; 
16mA 18/6 ; brand new at 
fraction of normal pri 
Full specs, supplied. 



(1) 



REGEKT-6 MW 
LW POCKET 
RADIO TO BUTLD 
S-TkBmMnf superhet. 
Geared tuning. Push-pull 
speaker output. Moulded 
cabinet 5 x S x liin. 
I'liwii.-S'.i'kft. CQ/C 
TOTAL COST u *'/ u 
TO BUILD P.P. 2,'- 

Full tuning on both bands 



SCR'S (THYRISTORS) 

• 1 AMP 8RSZB8 MIKE LEADS 

50P1V .. 7/6 100 P1V.. 7/61 

200 PIV 18/6 300 PI V.. 15/- 

100 PIV (280V Rim) 17/6 

100 PIV. 3 Amp Stud Type 

100 PIV. 7 Amp (280V Rms) . . . . 25/- 

100 PIV. 3 Amp 20/- 



DEAC RECHARGEABLE BATTERY. 
Your last chance for this offer. 
• 9.6 volt 225mA i'H .. .. 20/- pp. 1/6 



DEAC CHARGER 
To charge 3.6 volt and 9.6 vol! packs 
Fullv mains Isolated In case. P.P. 2/. 



, 45/- 



HI-FI 
EQUIPMENT 
Complete range In 
stock- Send list of 
requirements for 
special price quote. 

Hl-fl demoa*tration 
room open. 



VALVE AMPLIFIERS AND TUNERS IN CABINETS 



• SA100. 5 + 5 watt 
Stereo. 300mV Input 
FM Tunors, PU's, etc, 
O/P 4 to 10 ohms. Mains 



• SA200. 7! - 71 wan • AFM 100. AM I'M • AFM 200. AM FM 
version- Also Inputs tor tuner to match 8A1 00, tuner to match 3A200 

Mag.Mic.Mag.PU's,etc. etceeu-noweredmama. on nnc P-P- 

£27.10.0;?- £23.10.0 r p <£&"%*"•*» 

may In' used with any amplifier) 



AUofrotnjttoek: 

ARMSTRONG 

QUAD 

GOODMANS 

LEAK 

ROGERS 

TRUVOX 



(4) BUILD A QUALITY 2 OR 4 
V ' TRACK TAPE RECORDER 

3-speed version using new '363' decks 
©TWO-TRACK. Deck £10.10.0. Martin 
Amplifier £14.19.6. Cabinet and speaker 
7 gns. Complete kits with FREE 7in. 1200ft. 
tape, spare spool. 0"7 riric P,P- 

Today's Value £45 *•' y ,,J> 15/- 
#FOUR-TRACK. Deck £13.10.0. Martin 
Amplifier £15.19.6. Cabinet and speaker 
7 gns. Complete kits with FREE 7ln. 1200ft. 
tape, spare spool. Of\ nnc P - P ' 

Today's Value £50 ou a" 3 15/- 



TSA90. Transistor Stereo Amplifier in Case. 
4) +4j watts. 3tol6ohnisO,'p. Input 80mV 
TunerandP.U.'s.Mainsoperated. £Q 1Q fi 



(5) VHF FM TUNER TO BUILD 

87/105 Mc/s Transistor Superhet. Geared tun- 
ing. Terrific quality and sensitivity. For valve 
or transistor amplifiers. 4 «3Si 2jm. Com- 
plete with dial plate, 5 Mullard Transistors 
(FM Decoder Kit £5.19.6, P.P. 2,'-). 
TOTAL COST X»fi IDC P.P. 
TO BUILD l-O. IO.O om 

(Cabinet Assembly 20/- extra) 



2/6 



(6)- 



GARRARD DECKS- BRAND NEW FULLY GUARANTEED 



1000 mono £5 19 6 8F25 stereo £10 10 

ATS mono £8 9 6 8P25 Deram £13 10 

2000 mono £8 9 6 ATS0 less cart. £10 10 

20im stereo £6 18 6 AT60 mono £10 19 6 

3000 1m stereo £7 10 AT60 stereo £11 10 

SP25 less cart. £9 10 ATB0 Deram £14 10 

SP2I*. mono £9 19 6 LABS0 less cart. £27 



401 less cart./arm£27 10 
ATOmonoMkll £8 10 
ATI! stereo MkU £9 10 
AT6 Deram £12 10 

Deecadec Mk. II £17 17 
A70 less cart. £17 17 
(/'. & P. 51- any type) 



Allother 
makes of 
decks and 
cartridge 
In stock 



(7\ CLOBEMASTER MW/LW/SW 
V ' PORTABLE RADIO TO BUILD 

Full 3-waveband tuning. Pushbutton wave- 
change. Superhet printed circuit design. 
Black-chromed cabinet 11 x 7J. x 3jin. (SW 
17-50 metres). Ear/Record sockets. 1 wall 
Push/Pull output. 6 Mullard Transistors. 
TOTAL COST f7 I Q fi P.P. 
TO BUILD *-' ' '<*•** 3/6 



(8) TOURMASTER TRANSISTOR 
V ' CAR RADIO 

7-Translstor MW/LW Car Radio. 12 volt 
operated. 3 watt output. Push-button wave- 
change. RF stage. Supplied built, boxed, 
ready to use with Speaker and Baffle. Car 
fixing kit and manufacturers' currenl guaran- 
tee. Special Bargain offer. Buy Now! 

L,s « £9.9.0 pp 



Price 15 gns. 



3/6 



MARRIOT TAPE HEADS 

I Track It/RP/3 Med z, 7/8. R/RP/1 High z, 8/-. 
it'ltl'/l High z - R.'E/l erase or. block, 19/6. 
I Track L/RP8/12 High z. 15/-. L/RPB/7 
Med z, 19/6. L/E8/9 erase, 12/6. Also HR-RP 
Blnglc track Rec/Play Med z, 6/6. 



HENRY'S RADIO LTD. 

303 EDGWARE RD., LONDON, W.2 

PADdlnglon 1008/9 (STD. 01-723-1008) 

Open Man. to Sat. 9-6. Thurs. 1 p.m. 

Open all day Saturday 



SUPPLIERS OF DUALITY COMPONENTS AND EQUIPMENT FOR MORE THAN 20 YEARS 




1967 CATALOGUE 

(available end of January) 

Completely new and revised edition 
over 200 pages packed with com- 
ponents and equipment. Hundreds of 
new lines with data and illustrations. 
Complete with 5 Iree discount vouchers 
(total value 10/-) for use on purchases. 
The largest and most comprehensive 
range of items available. 
PRICE 7/6d. P. & P. 1/-. 
Hundreds ol new components, more 
information and illustrations.